When Napoleon finishes his "waterslide" presentation at the end of the movie, Ted looks up and says, "I don't think it's gonna work." If you look closely at the maps, you can see that Napoleon is actually diagramming the French invasion of Russia, Napoleon's most disastrous defeat.
When Bill reads the assignment to Ted, he says, "Express to the class how an important historical figure from each of your time periods would view the world of San Dimas, 1988." His lips are actually saying, "San Dimas, 1987" and the "1988" was dubbed later because of a delay in the movie's release.
Bill and Ted began as a stand-up act in which the characters would discuss current events without knowing what they were talking about. Originally there was a third character named Bob, but the comedian who played him lost interest after a few performances
In the original script, the time machine was a 1969 Chevy Van, but the filmmakers thought that it would be a rip-off of Back to the Future (1985). So, they changed it to a phone booth (apparently unconcerned that Doctor Who (1963) uses a police telephone box as its time machine). Also, when they used the van, Bill and Ted picked up more historical figures than they did in the final film.
Principal photography was completed in 1987, but the release was delayed because the film's original financiers, De Laurentiis Entertainment Group, went bankrupt. The film was in danger of being dumped onto cable television, until Nelson Entertainment bought the rights to the movie in 1988, and it was released in 1989.
During the report at the end, Bill mentions that he has an Oedipus Complex. This is a term first used by Freud to describe a child's desire to possess the parent of the opposite sex. This is a reference to Bill's confused sexual desire over his new stepmom, Missy.
On the cover of the British VHS re-release of the film (by BMG Entertainment International U.K. and Ireland Ltd. by Canal+ distribution) in 1997, there is a picture of Bill and Ted wearing tuxedos, linking arms with the Princess Babes. This is clearly from a deleted high school prom scene, which would have appeared near the end of the film.
Napoleon "pigs out" on a Neapolitan sundae at Ziggy Piggy's that he refers to as "La glacé". Even though there are similarities between the ice cream and his name, the dessert originated from Naples, Italy. Historically, Napoleon Bonaparte did in fact have a fondness for it, when he arrived in that country.
The rescue scene of Bill and Ted (their comrades pretending to be executioners and escaping on a horse-drawn carriage) is the same way that D'Artagnan is rescued in The Three Musketeers (1993), which was also directed by Stephen Herek.
The "Ziggy Pig" dish in the ice-cream restaurant is a reference to a comic book character put out by Timely Comics (later Marvel) during World War II. By the time this movie was made, it and its image (which appears on the badge they place on Napoleon's chest) were public domain. The award itself is based on the ribbon that could be won at Farrell's Ice Cream Parlor restaurants upon completion of their "Pig Trough," a double-sized banana split. Farrell's was a large restaurant chain in the 1970s, but few remained by 1988.
In the original outline for the movie, Rufus was a 28-year-old high school sophomore who befriended Bill and Ted. There was also a character named John the Serf, whom Bill and Ted picked up in medieval England.
In the book "The Producers: Profiles in Frustration," producer Scott Kroopf recalled pitching the idea of "Bill & Ted" to Dino De Laurentiis. Quoted Kroopf: "Dino had no idea what the film was about. He didn't understand what dudes were until someone said to him that 'dudes' meant guys who had big dicks. Then he said 'Oh, great, now I get it.'"
Though the film is PG, almost no cursing is heard in it, except for one quick spot that can easily be missed, and it's a whopper of a curse. At the end of the scene where Ted is enticing Genghis Khan into the phone booth with the Twinkie, right after Genghis walks off screen, you hear him yell, "You mother fucker" (with the last word sounding muffled). One of the other being when Ted asks Bill if they know where they're going, and after responding he doesn't know, Bill yells, "Shit!" while Ted just shouts.
The picture on Ted's t-shirt is the cover photo for Van Halen's "Why Can't This Be Love" single, for sale during the Van Halen 5150 tour and very commonly seen on Van Halen fans in the late 1980s. This was Sammy Hagar's first tour with Van Halen after replacing David Lee Roth.
The Circle K is in San Dimas at the corner of Walnut and Bonita Ave. The scenes at the convenience store were at least partially filmed at the Circle K at the northwest corner of Southern and Hardy in Tempe, Arizona.
The exterior shots of Bill and Ted's high school are of Coronado High School in Scottsdale, Arizona. The striking mosaic is featured on the school's auditorium facade and was designed by art teacher Mr. Gatti and the students in the early 1960s.
Australian band "Space Desert" have an EP called "Forrest Gump II", but none of the songs are about Forrest Gump. It is in fact about Bill and Ted, and even quote lines from the film, and include a snippet of an interview with Keanu Reeves and Alex Winter explaining the meaning of the word "Bodacious".
The trivia item below may give away important plot points.
During the scene where Bill & Ted are leaving Napoleon in Ted's younger brother Deacon's care, you can see an electric football game in the background. Assuming Ted grew up playing the game, it helps explain why Bill & Ted are good at it and can best the reaper when they play in the sequel.