This film is considered the "bridge" between the second and third seasons of The Transformers (1984), as several third-season characters are introduced here and several first-season characters are killed or altered (e.g. Megatron to Galvatron).
IDW published its own adaptation of the film in 2006. It includes extra scenes such as a battle between the missing combiners and Omega Supreme at the Ark and Shockwave and Reflector being destroyed by Unicron.
The band who sings the songs on the soundtrack called "Nothin's Gonna Stand in Our Way" and "Hunger" is listed on the soundtrack credits as Spectre General, but the band's name is actually Kick Axe. When the soundtrack was being assembled, they thought the name "Kick Axe" sounded too threatening, so they listed them as "Spectre General". The band was not notified about the change.
In season's 1 and 2 of the series, Megatron's first shot in gun mode always missed every autobot. Starscream using him to kill Brawn in the beginning marks the first and only time that his first shot hit an autobot and every shot also hit its target.
Both director Nelson Shin and story consultant Flint Dille have confirmed that, due to his failing health, Orson Welles had much difficulty recording all his dialogue for the film and all his recorded lines also included labored breathing and heavy wheezing. Shin considered all of Welles' recorded lines to be unusable but decided to put the recordings through a voice synthesizer to give Welles' voice a clearer, more ominous tone. According to Shin, Unicron's on-screen voice is not the "true" Orson Welles but instead, an enhanced, synthesized version of his voice.
In 2010, an early draft of the script got into the hands of Transformers fans, which reveal the plot of the movie went through many severe changes during writing. Even the characters themselves would have been different, and the movie would have been even more violent than the finished version.
Megatron (Frank Welker) is transformed into Galvatron (Leonard Nimoy). In the television seasons that followed, Welker took over the role of Galvatron. Welker had previously provided the voice (screams only) for Spock in Star Trek III: The Search for Spock (1984), which Nimoy appeared in and directed.
Orson Welles died in 1985, sparking rumors that Leonard Nimoy took over and provided the voice for Unicron. However, Susan Blu (Arcee) has since confirmed that Welles completed the voice-over work before he died.
Unicron's original name in early drafts was Ingestor, while Unicron's planet form would have been an actual planet. Ingestor was to be a mysterious being in control of the planet, which, upon transforming into a robot, would have had many organic-looking features. In the final script, these two were mushed together into a single character, named Unicron, who is also a planet (though a mechanical one) which can turn into a gigantic robot. His organic features were also kept, such as his metallic mustache and goatee, as well as his stomach that resembles the abdomen muscles of a human, though he lost his "hair".
Spike originally said "Oh s***, what are we going to do now" in the theatrical release when he and Bumblebee realized that blowing up the moon didn't affect Unicron. "Oh s***" had been put in the theatrical release to guarantee a PG rating as G rated movies could not be played as often during the day as PG, PG-13 or R rated movies back then. However, the line had been taken out of every VHS release until the Rhino re-release in 2000 and it was also restored in the 2000 Canadian DVD and the 2001 Rhino DVD released in the United States.
In the Japanese trailer of the film, the footage of Galvatron during the transformation of Unicron is slightly different: instead of Unicron dropping Galvatron in his mouth, he falls down a 'trapdoor' on Unicron. The scene where Kup tells the Dinobots the story about the the thick dust of Alpha-9 is also different. And more footage is shown.
During production, the idea of transforming the planet Cybertron into a robot to battle against Unicron came up, but was quickly dismissed. Interestingly, the Marvel Transformers comics (which told a separate storyline from the cartoon) did regard Cybertron to be the planet-form of the Transformer god Primus, whose backstory likewise involved warring against the evil Unicron. There was no connection between the discarded script and the comic series - different authors simply came up with the same general idea independently.
Two Cyclonus-style robots are created in the movie; one from Bombshell (Insecticon) and one from Skywarp (Decepticon jet). Many fans have speculated which one became the "real" Cyclonus. Cyclonus was (apparently) originally intended to have many duplicates under his command ("and his armada..."), like Scourge and his Sweeps. However, only one duplicate was created on-screen and was never seen again after that shot. This has led fans to write fanfics about a character called "Armada".
At the beginning of the movie, when the Autobots are taking off in their ship, Optimus Prime orders "Cliffjumper, commence countdown". The voice of Cliffjumper was that of Casey Kasem who was the host of America's Top 40 Countdown for many years. This was obviously a little joke by the writers.
Many of the second-season characters (Stunticons, Aerialbots, etc.) do not appear in the movie because they did not exist at the time the movie was written. However, they all suddenly appear in the post-movie episodes.
Originally, Ultra Magnus was dismembered by the Sweeps (his arms and legs were ripped from his body). This was changed to a scene of him being blasted to death. However, the shot of the Sweeps firing at Magnus shows them using continuous beams (almost as if they were ropes of energy), instead of laser blasts they are seen using in the rest of the movie.
The negatives for the matted wide-screen version of the film were either destroyed or lost, and for a time only the VHS full-screen version of the movie remained. The North Carolina School of the Filmmaking in Winston-Salem carries a print of the movie assembled from different reels of other prints of the movie found in its archives. The pieced-together print is in good condition. It should be noted that this wide-screen version of the movie was achieved by "matting down" the original full-screen animation, essentially chopping off the top and bottom.
Although Walker Edmiston is credited as voicing Inferno, the character is strangely absent from the movie. As revealed by an early working script, his sole line in the entire film would have been "Good luck, Magnus.", which was to be said during Galvatron's assault on Autobot City, as Ultra Magnus lead his Autobot troop to the space shuttles.
Originally, it was supposed to be Smokescreen who lay dead with Windcharger, not Wheeljack. Before the closeup of Windcharger's and Wheeljack's bodies, you can still see the body of a red-and-blue Autobot, meant to be Smokescreen, rather than Wheeljack.
Almost all of the new characters that appear in the movie were newly designed. The Hasbro toys were based on the movie's character designs. The exception was Ultra Magnus, who already had a toy in the Japanese "Diaclone" line. His character model was based on the toy, and given new colors.
Beachcomber can be seen inside Unicron right at the scene were Bumblebee and Jazz are on the claw. Hubcap is also seen right after that. Both show up later in the show with Beachcomber in "Five Food" and Hubcap in "Rebirth Part 3".
One potential plot proposed by writer and story editor Flint Dille and creative director Jay Bacal would have involved Optimus Prime embarking on a journey to discover the origin of the Transformer race, as well as find out that their home planet is actually a giant robot itself. Using the Matrix, the planet Cybertron would have transformed into a robot to face off against the evil Transformer planet Unicron, a pawn of the Quintessons. Their script was written in response to the original movie draft which they saw as incoherent, but was discarded shortly after presenting it to the executives. However, some elements of their script did turn up in the finished film, and a drastically reimagined origin story for the Transformers was detailed in the cartoon's third season - the Quintessons, minor one-scene villains in this film, were reimagined as the creators of the Transformers and had no ties to Unicron.
In the original script, "Life Sparks" would have had a very important role. No such objects are ever mentioned in the finished movie. However, a full decade later in Beast Wars: Transformers (1996), Sparks were canonically introduced into the Transformers franchise.
In the Marvel Comics adaption of the movie, Autobot City is referred to as Fortress Maximus. The character and toy for Fortress Maximus would not be introduced until nearly a year after the film's release.
In a bizarre kind of way, it could be said that the Decepticon 'Shockwave' appeared in two movies in 1986, the other being Aliens (1986). In the MedLab scene, just before Ripley reaches out to hug Newt after setting off the fire alarm, there is a futuristic piece of medical apparatus with three objects handing down off of it that can be briefly seen in the foreground. These objects are actually three Transformers toys, namely the Decepticon 'Shockwave' made by Hasbro in 1985 (though it's possible that the toy might even be the earlier 'Galactic Man' sold by Radio Shack). The toys have been spray-painted a dull silver colour and are displayed in their laser gun 'mode', but with each of the robot toy's arms (i.e. the laser gun's barrel) split apart. In this 'semi-transformation' the toy is made to look looks kind of like a futuristic grasping tool or perhaps even a laser scalpel.
The trivia items below may give away important plot points.
The movie was being produced by the same company, and at the same time, as G.I. Joe: The Movie (1987). It had been agreed that both movies would suffer the loss of the lead heroes, Optimus Prime and Duke. Production had begun on G.I. Joe first, and was thus expected to be released first. During the production of the two films, G.I. Joe was held up while Transformers finished production. Release dates were changed and Transformers got theatrical release in 1986. Optimus Prime's death sparked some controversy and caused the writers to change Duke's death to a coma. G.I. Joe never got to the theaters, and was released to video instead. Had G.I. Joe been released first, Optimus Prime might have survived.
Optimus Prime's death become something of a running gag later on. Almost every transformers series, (including Beast Wars) features Optimus Prime (or his equivalent) dying, only to be resurrected some time later.
The movie kills off many of the original characters: Optimus Prime, Ironhide, Ratchet, Prowl, Brawn, Wheeljack, Windcharger, Megatron, Starscream, Skywarp, Thundercracker, Shrapnel, Kickback and Bombshell are all casualties, and it is learned in the third season that Huffer also died at some point off-camera during the movie.
An earlier script version included a very interesting scene that detailed what the Autobots that remained on Earth, such as Blaster, Sunstreaker, Trailbreaker, and Wheeljack (who by this point was killed in the final script) had to go through. The would have fought a guerrilla-war with the Decepticons sieging Earth, and the existence of the planet itself was to be threatened. In the finished movie, the Decepticons leave Earth alone after the two Autobot shuttles take off.
The non-finalized script that the fans got a hold of details the deaths of some characters in a more graphic fashion. For example, originally Gears was to be bombed to pieces (he only has a cameo in the finished movie), and Windcharger would have been shredded to bits by Cyclonus, his parts raining on top of his companion, Blaster. In the finished film, we don't see him die, only his corpse.
Four other characters were scripted to die in the film as well, but the scenes were not animated. During the attack on Autobot City by Devastator, Ultra Magnus attacks, accompanied by Sideswipe, Tracks and Red Alert, and Red Alert is killed by a cannon blast. Mirage would shoot Bombshell, only to be blasted by Megatron, and Trailbreaker's dead body would lie on the ground as the Decepticons scramble aboard Astrotrain. Also, towards the end of the movie when Shockwave is frantically calling for the Decepticons to engage Unicron, Unicron's hand was supposed to have been seen crushing Shockwave's citadel. The way the movie was released, after Shockwave calls "Scramble!", Unicron's hand comes down and smashes a good part of the planet's surface, and Shockwave is never seen again.
The early script also explained the death scene of Optimus Prime differently. Since the Matrix of Leadership hadn't been "thought up" at that time, Optimus Prime would have handed over an entirely different object to Ultra Magnus: namely, his own "essence". A white-colored Optimus Prime would have emerged from his body to take place inside Ultra Magnus. This idea clearly originated from Ultra Magnus' toy form, which was basically just a white version of Optimus wearing blue and red colored armor. The final script re-wrote this scene, thus the inner white "Optimus Prime" of Ultra Magnus never got referenced in the cartoon. However later incarnations of the character frequently depicted him as nothing more than a white Optimus Prime.
The death of Unicron (or as he was then called "Ingestor") would have been much different, according to the early draft. Since the Matrix was absent from that version, Ingestor essentially caused his own demise by inflicting great damage upon himself.
In one of the early scripts, Megatron and the other damaged or dead Decepticons would have made it to Cybertron, specifically the Decepticon Hall of Fame (where Starscream's coronation takes place in the finished film) and fought over leadership. During their fight, Megatron would have been crushed by a falling statue with only his Life Spark remaining. Several ancient Decepticon Life Sparks would also have been accidentally released, drifting into space. These were to be then made into Galvatron's troops by Unicron when Megatron's Life Spark met him. Remnants of this scene did end up in the movie: for example, many Decepticons who were supposed to have been killed appear alive at the coronation, since in the early drafts they were indeed alive at this point.