Continuity mistake: Right when the movie begins, a machine opens a dog food can and then pours it in the dog's bowl. When pouring the food, the can isn't moved around at all, but after the food drops, the label is missing a piece. (00:02:25)
Continuity mistake: At the beginning, when Michael J Fox is cranking up the amplifier, the dial marked "Primary power" initially rises from 100 - 120, then when he turns the "overdrive" knob, it's back at 110 and goes to max. (00:03:15)
Continuity mistake: In 1955, when George walks into his house, Marty thinks of Mystery Science Theatre and looks at the vanishing photograph, and at the dance, after George punches Biff and rescues Lorraine, again Marty looks at the vanishing photo. In these two close-ups the thumb holding the photo looks nothing like Marty's thumb/nail in other close-ups, such as when he powers up the amp at Doc Brown's at the start. (00:03:15 - 01:23:45)
Continuity mistake: After Marty has been thrown into the bookshelf after the amp explodes, he is lying on the floor with his left leg bent at the knee. In the very next shot however, he has not moved but both legs are straightened and on top of each other. (00:04:05)
Continuity mistake: After the shelves fall on top of Marty, the rubbish on top of him changes between shots. (00:04:10)
Continuity mistake: Some of the items in Doc's lab change position between the shots of Marty standing in front of the amplifier and it exploding. (00:04:15)
Continuity mistake: When Marty's been thrown back by the amp, the papers on top of him change between the first and second shot. Precisely a Polaroid photo, a poster/map and a vase are missing. (00:04:20)
Continuity mistake: Marty is hitching a ride on the back of a jeep, a wide shot shows him going past and beyond the 'Lou's Aerobic Fitness Center' next to the Texaco garage, there's a cut to his skateboard then back to a medium shot of him going pass the same fitness centre again, this time waving to the people inside. (00:06:00)
Continuity mistake: When Marty is riding his skateboard to school in the beginning, he waves to a driver and you can see his wearing a watch on his left hand. However, look at his left hand when he meets up with Jennifer, and you'll see that it's gone. (00:06:10 - 00:07:00)
Suggested correction: There's a time-lapse directly before Marty arrives at school. There was plenty of time for him to remove the watch offscreen.
Continuity mistake: After the scene where Marty and his band are rejected from the school tryouts, Jennifer and Marty are sitting down and a lady comes by and asks them for change to save the clock tower. After they attempt a kiss, Jennifer's dad calls for her from the car. In the background, an African-American man is standing looking in the window of a building, and then walking right. In the next shot, he has moved all the way to the left and is walking right. (00:10:30)
Continuity mistake: After Marty drops a quarter in the clock tower fund can, he briefly rests his right hand on top of its red lid. But at the next angle, his left hand is on the lid instead. (00:10:45)
Continuity mistake: Marty's hairstyle changes when Jennifer kisses him on the town square bench. (00:10:45)
Continuity mistake: Marty has a brainwave about how to generate the power needed to get back to 1985, and shows Doc the flyer he was given, which Jennifer had written "I love you" on the back of, with her number. Problem is that after Doc grabs the flyer, we can see the back of it, and it's totally blank. (00:10:55 - 00:52:05)
Continuity mistake: When Biff is grousing to George about who will pay his cleaning bill (for spilling beer on his jacket when he wrecked George's car), there is a picture frame on a stand in the background. It's initially facing fairly rightwards, but in the next shot of the argument, it's facing more towards the camera. (00:11:55)
Continuity mistake: When Marty's coming home at the beginning of the film, he's watching the discussion between his father and Biff who complains about the wrecked car and his reports. In the two shots which show Marty, there's a glass full of candies near to him. When Biff steps to the glass and lifts the lid, half of the candies are gone. (00:12:15)
Continuity mistake: George McFly's holding a pen in his right hand, then a cut to a wide shot reveals him not holding a pen as he rests his arm away from his body on the table. Then when the camera cuts back his arm is back in front of him holding the pen. (00:14:10)
Continuity mistake: At the beginning of the movie after Biff leaves the McFly home. There is a scene where Marty and George are talking. In one shot George has three pens in his pocket, a few seconds later he has two. (00:14:14)
Continuity mistake: After Lorraine drops Uncle Joey's cake on the kitchen table, Dave can be seen resting both hands on the back of his chair. When the shot changes, both of his hands are elsewhere. (00:15:00)
Continuity mistake: When the McFlys are together in their kitchen, Lorraine asks everyone to drop Uncle Joey a line. At this point George lowers his left hand and seemingly reaches for silverware on the table. But between shots, he lifts his hand back to its original position all of a sudden. (00:15:00)
Continuity mistake: During dinner, when old-Lorraine says "We all make mistakes in life, children", she swaps from having one hand on the glass to both hands, between one frame and the other. (00:15:06)