Bill charging the knight when he thinks killed Ted.
Bill: YOU KILLED TED, YOU MEDIEVAL DICKWEED!
The historical figures running amok in the mall.
Especially Billy and Genghis Khan for lasting the longest.
Beethoven is introduced to synthesisers, immediately sees their potential and is soon playing a symphony on several keyboards all at once in the music shop, attracting a huge crowd.
Sigmund Freud psychoanalysing the police interrogator and driving him up the wall.
Interrogator: Look, I want to know why you claim to be Sigmund Freud.
Freud: Why do you insist I'm not Sigmund Freud?
Interrogator: Why do you keep asking me these questions?
Freud(leans forward): Tell me about your mother.
The scene with the future council. Words cannot describe.
Sadly, the version of Robbi Robb's "In Time" that plays in this scene (with the awesome, awesome lead guitar) is commercially unavailable. It is up on Youtube, however, and there are multiple ways to extract an .mp3 file from it.
The band's unofficial mantra "Be Excellent To Each Other And Party On" also qualifies. No matter how ditzy the guys are, it's hard to deny that it's a most excellent philosophy to live by.
That music playing after Napoleon got kicked out of the bowling alley and walks proudly while putting his hat back on.
The entire scene where they give the report. One of the great climaxes in film history, and if you're a history student (or just any kind of student), face it: you want to give a report like that.
Bill & Ted's Bogus Journey
The climax of the sequel qualifies. "God Gave Rock and Roll To You", indeed.
Unfortunately, that version of the song (with Bill & Ted's guitar solos at the start) has never been commercially released, but Steve Vai's guitar solos & the KISS song have. Fans have managed to replicate the song as featured in the film with a little editing, and a little searching on the internet can bring up mp3s of the song with the solos at the start.
In a shooting script (and comic adaptation) for Bogus Journey, the boys had to confront their fears when the Evil Robot Usses make them manifest in the real world-Bill accepts a kiss from Granny Preston, Ted apologizes to Deacon and returns the Easter Basket, and both of them invite Colonel Oates in for snacks. They also fought their evil doubles hand-to-hand until the Good Robot Usses could get to them.