Continuity mistake: When Marty is on Strickland's porch with the shotgun pointed at him, his hands go from in the air to down by his waist in a split second.
Continuity mistake: Int the courtyard chase scene when Griff and gang crash through the courthouse windows, the sun's position changes in every shot.
Continuity mistake: When Strickland is hitting Biff with the Almanac in the parking lot, the way the book is folded changes between shots.
Factual error: When Biff and Marty discuss the Almanac in the Alternate 1985, a magazine is visible. This is the March 1989 issue of "Mustang."
Continuity mistake: When Marty confronts Biff in the alternate 1985 in the hot tub, the girls change positions. The blonde was on his left and the brunette was on his right. When they see Marty and scream, they move forward but there is no way they can switch that fast. (00:55:40)
Continuity mistake: When Marty kicks the amplifier over when onstage at the dance in the first BTTF film the amp was sitting on an upside down Pepsi Cola crate. In BTTF 2 there is no crate then the amp is on the floor.
Suggested correction: At no point in the first movie is the amplifier on a crate.
Audio problem: When Marty is watching himself talk to Lorraine after playing Johnny B. Goode, you can see and hear Lorraine, "I hope you don't mind but George asked me if he could take me home" but watch her lips and listen. It's way out of sync.
Audio problem: When Marty follows Biff into the dance hall trying to get the sports almanac, right after he uses his binoculars he exits the dance hall. If you listen carefully to the music, the music plays uninterrupted, when given the jump in scene it should skip to a further point in the song.