Continuity mistake: After Spider-Man recovers from the train incident, Doc Ock smashes in the other end of the train and throws the door on the floor in front of him. The camera cuts to another shot, and when it returns the door is no longer on the floor, nor is it there for any subsequent shot.
Continuity mistake: During the final conversation between Spider-Man and Doc Ock, the rips in Spider-Man's suit keep changing. For instance, there is a tear on his right shoulder; for most of the scene, there is a single piece of black webbing left holding the rip together, but when Doc Ock grabs Spider-Man's arm, the rip now has two pieces of black webbing. Then it goes back to one.
Continuity mistake: In the scene where Peter is riding his scooter to Mary Jane's play, after the music fades out you see a black convertible being chased by several police cars. The black convertible is rammed forcibly, and you see many hideous dents on the side of the car. Thirty seconds later, after Peter is done talking to the kids, we see the same car from the same side it got rammed into, but the hideous dents have vanished.
Continuity mistake: As Peter stops the elevated train with many webs, a tear appears in his suit on the inside left arm during a closeup. Later, when his arms are still outstreched, there are many shots where you can see that the tear has disappeared; for example, a few shots later when he is still trying to stop the train; when the passengers are lifting him over their heads into the train; and many others.
Continuity mistake: On his last pizza delivery before he gets fired, when it first cuts to the receptionist and the room that she is in, the clock is very high up in this shot, above the receptionist's head, then in the following shot when the receptionist is looking in Peter's direction, the clock is much lower.
Continuity mistake: Just after the bank robbery, Spider-Man and Doc Ock are on the side of the building. Doc Ock says "oops, butterfingers." Spider-Man shoots a web to catch Aunt May. In this shot, Spider-Man is on one knee with the other one resting on the wall, yet in the following shot he is standing up and leaning back to pull Aunt May up.
Continuity mistake: When Doc Ock carried MJ up the side of the building after he kidnapped her, one of the D'Agostino banners was ripped out of the building and fell. But when Peter came out of the deli and looked across the street, the banner was back on the building and the building wall showed no sign of damage from Doc Ock's tentacles.
Continuity mistake: Just after the car goes through the cafe window and almost hits MJ and Peter, they both get up and most of MJ's hair is blown back over her shoulders. However, in the following shots, there is now a lot more at the front of her shoulders, than in previous shots. Throughout the movie, her hair changes position in consecutive shots.
Continuity mistake: Close to the middle of the film when Peter is in the big room where MJ announces her engagement, when Peter is finished talking with Harry at the bar he gets pulled away by Jameson, Harry then turns around and drinks, yet when it cuts to a shot of Peter and Jameson walking away, look in the background and Harry is still looking at Peter walking away.