During filming in a neighborhood in Louisiana, the cast and crew were often greeted by local residents. One day, Keanu Reeves noticed a sign on a lawn that read "You're breathtaking". He stopped, got out of the car, went to the sign and autographed it. After finding out who the sign belonged to, he went to the family and posed for a photo with them.
In May 2020, Alex Winter launched a social media appeal for members of the public to submit 30-second video clips of themselves rocking out to a music clip from the film, with some of the clips being selected and used in the finished film.
In this film, Kelly is Rufus' daughter. The late George Carlin played Rufus in the first two Bill & Ted films and his real-life daughter's name is Kelly. The "Kelly" role is named as a way to recognize and honor Carlin.
Alt. Rock band Weezer released an original song Beginning of the End (Wyld Stallions Edit) as the first single for the film's soundtrack on August 14, 2020. Weezer's first gig was a closing act for the Alt. Rock band Dogstar in 1992, which Keanu Reeves was a member of at the time.
During the final concert scene, you can see a billboard for "Circle K". Outside a Circle K is where Bill & Ted meet Rufus for the first time in Bill & Ted's Excellent Adventure.
Dave Grohl: The guy who asks Bill and Ted who they are and what they are doing in his house is played by the lead vocalist and guitarist of Foo Fighters and former drummer of Nirvana, whose breakthrough album "Nevermind" was released just two months after Les folles aventures de Bill et Ted (1991).