Some shots of the whales were in fact four foot long animatronics models. Four models were created, and were so realistic that after release of the film, US fishing authorities publicly criticized the filmmakers for getting too close to whales in the wild. The scenes involving these whales were shot in a pool underneath a Paramount parking lot. The shot of the whales swimming past the Golden Gate Bridge were filmed on location, and nearly ended in disaster when a cable got snagged on a nuclear submarine and the whales were towed out to sea.
The woman who answers Uhura and Chekov when they are looking for the "nuclear wessels" was an extra who was not supposed to speak. Layla Sarakalo had never acted before and was told to "act naturally". So when she was asked, she improvised an answer. Much to Sarakalo's surprise, her unscripted line was kept in the film. Sarakalo happened upon the set when her car was towed away to make room for the film's production. Sarakalo offered to be an extra so that she could make money to get her car back.
A scene written for but cut from the film explained why Saavik stays on Vulcan: she is pregnant with Spock's child, stemming from an event in Star Trek III: The Search for Spock (1984). This was the character's final appearance in a Star Trek film.
Catherine Hicks says she knew absolutely nothing about Star Trek before being cast in the movie. She credits Leonard Nimoy with pausing in her auditions to explain things about the series, and says she opted against watching episodes of the television series or previous movies after getting the part. Hicks credits her unfamiliarity with the Trek franchise as making Gillian's "outsider" encounter with the Star Trek universe more natural.
The idea of having Spock give the Vulcan nerve pinch to the punk rocker was inspired by Leonard Nimoy who was walking down the street in New York when a punk came out of a store with his boombox blaring, disturbing everyone around him. Annoyed, Nimoy thought "If I was REALLY Spock, I'd pinch his head off!" (According to Nimoy in the DVD commentary).
The film was originally supposed to have Eddie Murphy instead of Catherine Hicks. Murphy was supposed to have played a professor concerned with UFOs who spots the decloaking Klingon ship at the Super Bowl. Apparently, all others are convinced the ship is a half-time special effect while Murphy believes it is real. Paramount declined this script for two reasons: Paramount didn't want to combine their two most profitable franchises (Star Trek (1966) and Beverly Hills Cop (1984)), and Murphy had signed on to do The Golden Child (1986) instead.
Sulu (George Takei) was supposed to leap into the Huey helicopter when the pilot was outside, looking the other way, and make off with it. Takei had just run the San Francisco marathon when they were supposed to shoot this scene, and was too sore to leap into the helicopter. They tried having a grip throw him in, but couldn't get it to look realistic, so the scene was cut. In the final edit, Sulu is shown talking to the pilot, then shows up flying the helicopter a few minutes later.
The captain of the USS Saratoga, seen at the start of the film, was the first female captain ever seen in a Star Trek story. The success of this film led to offers by several US television networks to produce a new Trek television series with the original cast. Instead, Paramount gave the green light to produce the syndicated Star Trek: The Next Generation (1987) starring an all new cast. A woman (Kate Mulgrew) was cast as ship's captain in the spin-off series Star Trek: Voyager (1995).
The film bore the dedication, "The cast and crew of Star Trek wish to dedicate this film to the men and women of the spaceship Challenger whose courageous spirit shall live to the 23rd century and beyond..." This was a reference to the Space Shuttle which exploded over Florida on January 28, 1986 killing all hands.
Leonard Nimoy has said that when the film first came out, whaling rights activists caused an uproar. These groups felt the effects and models portraying the whales was actual footage, and that actual whales were held in captivity or filmed too close to their habitat.
The film marked Majel Barrett's last appearance as Christine Chapel. A year later, she would begin her recurring role as Lwaxana Troi on Star Trek: The Next Generation (1987), and provide the computer voice on TNG and other later Star Trek series.
William Shatner was originally reluctant to return to the Star Trek franchise. Leonard Nimoy and Harve Bennett considered making a prequel with the characters at Starfleet Academy. Eventually, Shatner was offered a pay raise in order to convince him to return. As a result of Shatner and Nimoy's raised salaries, Paramount had to lower the budget of its new series, Star Trek: The Next Generation (1987).
According to George Takei, when McCoy, Scotty and Sulu are standing in front of the building with Yellow Pages advertisement, a door opens and an Asian woman appears. The scene in the movie ends at this point but originally this woman was to begin shouting for a young boy named Hikaru, who would run into Sulu. Sulu would realize that this boy was his great-great-(etc.) grandfather. The young boy hired for this scene began to cry on the set before the shot and they were unable to get him to do the scene. With no one to replace him, the scene was never shot.
The restaurant scene was filmed in an actual restaurant. It didn't have a pizza oven but, because the characters order pizza, Paramount bought and installed a pizza oven to make the kitchen more believable. The oven was given to the restaurant after filming was completed. But after all that effort, the oven is never visible in the film.
When the alien ship is approaching Earth at the beginning to look for the humpback whales, there were originally subtitles saying things like "Where are you? Can you hear us?". The studio wanted to keep them despite Leonard Nimoy's objections. However, in the first test screening, test audiences indicated the subtitles were unnecessary so they were cut.
The antique glasses that Kirk sells to make some cash are the pair that was given to him by McCoy for his birthday in Star Trek II: The Wrath of Khan (1982). It's suggested that once sold in the antiques store, those glasses hang around until they're bought by McCoy, in the future, and then Kirk takes them back in time, and so on, in which case one has to wonder where the glasses "originally" came from. This constitutes an "ontological paradox", an old favorite of science fiction writers, and raises too many questions to discuss here. (It is possible that these glasses existed in two places simultaneously, like characters in the "Back to the Future" films, rather than being caught in a causal loop.) The same paradox arises when Scotty explains how to make transparent aluminum. If the formula is "found" for the first time in the 20th century, but only because Scotty took the information back, then it was never invented in the first place! (This may not be a paradox if Scotty only gave Doctor Nichols the chemical formula but not the manufacturing process.)
Majel Barrett and Grace Lee Whitney make brief appearances as Christine Chapel and Janice Rand, beloved Star Trek (1966) supporting characters. Both can be seen at Starfleet Headquarters during the Probe's arrival.
Gene Roddenberry was initially pleased to hear the movie would be a time travel story, as he had been pushing for such a plotline in one of the movies. However, Roddenberry had long wanted a story in which the crew traveled back in time in an attempt to stop the assassination of President Kennedy, but Harve Bennett felt such a story would be anticlimactic with the audience knowing such a historical event could not be undone.
When Spock takes the test on his homeworld, there is a question that asks: "What were the principal historical events on the planet Earth in the year 1987?". The answer is not heard but you can see two answers written by Spock. "Computers cloned from carrots." And "New York Times is last magazine to close doors." Then the computer answers "Correct".
One early draft script was subtitled "The Trial of James T. Kirk". This script involved Kirk being court-martialed at the request of the Klingons, who were indignant about the events in Star Trek III: The Search for Spock (1984). One particularly interesting facet of this script is that it included the character of Harry Mudd (Roger C. Carmel) as a character witness. When the time-travel script was approved instead, the trial was included as a minor sequence. The trial-by-Klingons idea (and portions of the dialogue) was later re-used in Star Trek VI: The Undiscovered Country (1991).
When Nicholas Meyer was asked to help with the script, the first thing he wanted to do was change the location from San Francisco to Paris because he had previously written and directed a movie about time travel involving San Francisco called Time After Time (1979). But since Starfleet is supposed to be located in San Francisco, he was overruled. Oddly enough, scenes in Star Trek VI: The Undiscovered Country (1991), as well as scenes from Star Trek: Deep Space Nine (1993) depict the Office of the Federation President to be in Paris.
The scene where Chekov and Uhura are asking a woman about "nuclear wessels" was almost completely improvised. Her line about them being in Alameda was ad-libbed by her, and although she wasn't supposed to say very much, Leonard Nimoy enjoyed the spontaneity of the scene so much he left it the way it was.
In the bus scene, there is a man in a brown jacket sitting just in front of the "loud punk". He can be seen "reading" the latest issue of Omni Magazine, which from 1978 to 1998 published articles on scientific developments as well as short works of science fiction. The specific issue in this scene is from May 1986; the cover celebrates the "25th Anniversary of American Manned Spaceflight".
In overseas markets, the title was inverted to The Voyage Home: Star Trek IV, which featured a lesser emphasis on the Star Trek branding. This was due to the poor overseas box office results of the previous Star Trek movie.
William Shatner and Leonard Nimoy improvised the continuing "Yes" "No" response to Gillian's question about liking Italian. Initially, Kirk was to say "Yes" at the same time Spock said "No", but the actors came up with the alteration while filming the scene.
Saavik is only featured in the first quarter of the movie. The character was "left behind" on Vulcan by the filmmakers as they didn't really know what to do with her in 20th century San Francisco. In particular, Leonard Nimoy and Harve Bennett felt her to be too extraneous, and saw the redundancy of having to hide a second Vulcan's identity while on Earth in the past.
The Plexicorp scenes were filmed at the Reynolds and Taylor Plastics factory in Santa Ana, California. The company's acrylics division makes large custom plastic panels, and one of their clients is actually the Monterey Bay Aquarium.
When Kirk, McCoy and Gillian first enter the hospital and are walking around trying to locate Chekov, a voice on a loudspeaker in the background says "Paging Dr. Zober... Dr. Sandy Zober." Sandi Nimoy (nee' Zober) was director/star Leonard Nimoy's wife at the time.
The officer on the Saratoga who announces that the thruster controls are offline is of the same alien race as the Federation President in Star Trek VI: The Undiscovered Country (1991). This race has never been officially named, but some promotional materials identify the race as the Efrosians (named after Mel Efros, unit production manager for Star Trek IV: The Voyage Home (1986)).
For the shot of Sulu flying the helicopter over San Francisco bay, the filmmakers tried to get a pilot to fly a Huey, but they were unable to. The long shot was accomplished using a radio controlled model from Japan.
In order to find the best actress to play Dr. Gillian Taylor, two prospective actresses were brought out to William Shatner's ranch by Leonard Nimoy to meet with the man himself. It was Shatner who personally chose Catherine Hicks saying that she was "spunky" (According to Shatner and Nimoy in the DVD commentary).
The computer that Scotty uses in the Plexicorp scene appears to be a Macintosh Plus, but its internals were completely changed for filming. Its screen was replaced with one from an IBM PC to make it easier to synchronize its video refresh rate with the film camera's frame rate, and the "transparent aluminum" animation was created on an IBM PC by computer graphics company Video Image.
The older triangular building in the background of the San Francisco street corner scene was built in 1907 and was at one time home to a restaurant named Caesar's, one of the alleged birthplaces of the Caesar Salad. The building is now owned by Francis Ford Coppola and is mostly occupied by American Zoetrope Studios and Cafe Zoetrope.
One of the extras in the Cetacean Institute tour scene (brunette with brown vest) is also visible at the left edge of the frame in the last shot on the Enterprise bridge. She had also appeared as an extra in the previous two Star Trek films.
Leonard Nimoy came up with the idea of using humpback whales after reading a book about extinct animals. Nimoy realized that their song added mystery and their size added a challenge for the crew to overcome. Nimoy previously considered a story about a disease that could only be cured by the rain forests but decided that he wanted to keep the film's tone light-hearted.
Outside of North America, the film's title was changed to "The Voyage Home: Star Trek IV". This was done because Star Trek III: The Search for Spock (1984) had done very poorly outside of North America. A special prologue narrated by William Shatner was created in which Kirk recaps the events of Star Trek II: The Wrath of Khan (1982) and Star Trek III. The film ended up grossing only slightly higher than Star Trek III outside of North America.
The scene in which the Bird-of-Prey lands in Golden Gate Park was actually shot in Will Rogers Park in Los Angeles. The filmmakers had planned to shoot in the real Golden Gate Park but heavy rains made the field muddy.
First movie appearance by Spock's mother Amanda, and only Star Trek movie in which she was played by Jane Wyatt, who originated the role. While Spock's father Sarek also appears in the movie, he and Amanda share no scenes together.
First Star Trek movie since Star Trek: The Motion Picture (1979) to be released for the holiday movie season as opposed to the summer. This was largely due to William Shatner having become free of his commitment to the television series T.J. Hooker (1982), which had been canceled.
Leonard Nimoy said there were some suggestions of using subtitles to translate the communication between the Probe and the whales for the audience. Nimoy objected to this, feeling it would too greatly diminish the sense of mystery regarding the Probe and its connection with whales. However, the novelization did depict a translation.
San Francisco was chosen as the setting largely due to it's proximity to the studios in Los Angeles for location shooting, and the fact that Starfleet Headquarters is based in San Francisco. The setting was also likely a hold over from the original drafts which had scenes depicting a Super Bowl. Super Bowl XIX was played in the San Francisco area not long before the first drafts were written.
Harve Bennett wrote the beginning and the ending of the script while Nicholas Meyer wrote the middle scenes which take place in San Francisco. Steve Meerson and Peter Krikes wrote the original screenplay, and while most of their ideas were deleted, they still receive credit.
During Spock's memory tests, the computer speaks very rapidly, almost too rapidly to discern. The first question it asks Spock is, "Who said 'Logic is the cement of our civilization, with which we ascend from chaos, using reason as our guide'?"
Leonard Nimoy found making the movie challenging at times as he had to alternate his energies and enthusiasm in directing the film, with simultaneously stepping into the role of the emotionally reserved Spock.
Some questions from the test Spock takes on Vulcan at the beginning of the movie: Q Who said, "logic is the cement of our civilization with which we ascend from chaos using reason as our guide". :A T'plana Hath. Q what os the molecular formula of sulfite crystals. Q What significant contribution to bioengineering was made in Lucarian Outpost on Klendth. A The universal atmospheric element compensator. Q: Adjust the sinewave of this magnetic envelope so that antineutrons can pass through it but antigravitons cannot. Q: What is the electronic configuration of gadolinium.
Kirk R. Thatcher:
an associate producer plays the punk on the bus who is nerve pinched by Spock. Thatcher expressed displeasure at the music chosen for his boom box, and asked to write and perform a song that he felt would be more representative of his character. The result was the song "I Hate You".
The Go-Gos rhythm guitarist appears as a communications officer on a starship rendered powerless by the Probe. She is seen on the right of three huge video screens amid a chaotic control room on Earth. Her line: "The condition remains the same. The Probe has neutralized all power supplies. We are functioning on reserves only".
The trivia items below may give away important plot points.
Humpback whales, when they sing, move into an upside down vertical position as correctly depicted in the movie. After hearing the humpback response, the alien probe also moves into this same position and replies.
During the final scene of the movie, where the Enterprise crew is in the shuttle Sulu says "with all respect, I'm counting on Excelsior." In Star Trek VI: The Undiscovered Country (1991), Sulu is the Captain of the Excelsior.
During the film's 1 hour 59 minute runtime, there's only a total of about 1 minute 13 seconds worth of shots of the Enterprise - the shortest amount of time the Enterprise is seen on screen in any Star Trek movie. The first 33 seconds of it during the beginning courtroom scene was stock footage of the Enterprise's destruction from Star Trek III: The Search for Spock (1984). The other 40 seconds of it were shots of the Enterprise-A towards the end.
It is often claimed that this is the only Star Trek film where no weapons are fired. This is incorrect, as Kirk uses his phaser to weld a door shut, and the whaler fires its harpoon. Chekov also tries to use his phaser, though it doesn't work. It is also one which no cast member from this film is killed, as the only deaths were from the reused footage from Star Trek III: The Search for Spock (1984).
While attempting to escape from the security agents aboard the USS Enterprise, Chekov tosses his phaser to one of the agents; although it is representative of 23rd century technology, it is never retrieved.
Early in the film, the President of the Federation tells the Klingon Ambassador that Kirk is charged with nine violations of Starfleet Regulations. At his court-martial at the end, only six charges are listed: 1. Conspiracy, 2. Assault on Federation Officers, 3. Theft of Federation Property (the Enterprise), 4. Sabotage of the Excelsior, 5. Destruction of Federation Property (the Enterprise again), and 6. Disobeying direct orders of a superior officer.
The computer graphic consoles that became standard on the 24th century Star Trek bridges and also called "Okudagrams" (named for designer Michael Okuda), make their first appearance on the bridge of the USS Enterprise NCC-1701-A. It is also the final appearance of the entire original Star Trek movie bridge set as only small parts were reused for Star Trek V: The Final Frontier (1989).
Uhura is the only crew member in duty uniform. Everyone else (except Spock) is dressed in Starfleet, casual wear. Saavik is also in uniform, but stays behind. Chekov leaves his civilian clothes in the past.
The original script called for the whales to be intercepted during aerial transport over the Golden Gate Bridge. San Francisco Mayor Dianne Feinstein objected, saying that the city already had enough trouble with jumpers on the bridge, and that the scene would only encourage more. This led to the scene showing capture of the whales in Alaska.