Although Jason Marsden is a talented singer, he did not perform the musical numbers in the film. It was out of Disney's concern that a Broadway-style musical actor should provide Max's singing voice instead.
HIDDEN MICKEY: During the Powerline Concert, Mickey Mouse can be spotted in the crowd in the lower left portion of the crowd shot immediately after the Stage manager is thrown into the DiamondVision screen. Also, Mickey Mouse can be spotted during the show in the auditorium, when Max flies towards Roxanne, in the left bottom corner, right after the camera focuses the whole room.
WILHELM SCREAM: Twice. First, dxring the "On the Open Road" song, Goofy's car crashes into a construction scaffolding and the famous scream can be heard. Can be heard again during the Powerline concert when the stage manager chasing Max is thrown into the DiamondVision screen.
When Goofy and Max are in the bat caves taking a photo of themselves with flash (which causes the bats to fly out at them), you can see that the sign above the caves as they're running out reads: "Carl's Butt Caves".
Throughout the film, Goofy is only referred to by his real name once--- by Pete, when they meet at the latter's trailer. Otherwise, he's referred to as "Dad" (by Max), "Mr. Goof" (by Max's Principal), or just "Goof" (by Pete).
There are several references to Disney characters, including Max saying Goofy's 'best buddy' is Donald Duck, and a cardboard prop with Ariel from _The Little Mermaid (1989) _qv) after Max gets "busted".
This film was originally made around late 1993, and was supposed to be released in theaters during the holiday season of 1994. However, some production problems in France caused the film's release to be pushed back to 1995, while The Lion King (1994) was reissued to fill in for the film's absence.
GOOFY HOLLER: The cartoon equivalent of the famous "Wilhelm Scream" can be heard as the movie opens and the title is shown on screen. Again at the end of the movie after Goofy's car explodes and he's sent flying upwards, then plummets back to the ground. The scream is heard one more time after the credits roll.
When Max is singing in the school auditorium, Roxanne's position changes from close to the stage to the back of the room. The reason the filmmakers did this was to give the allusion that all Max really cares about is Roxanne and really no one else.
The trivia item below may give away important plot points.
In the scene after Big Foot attacks Max and Goofy, Max kicks the glove box and the map falls out. Max, then, looks at it. The starting location is around the area of Columbus, Ohio, answering a question that's been around for ages: "Where does Goofy live?"