In the scene where Mary Jane is being mugged by four men, Spider-Man throws two of the men into two windows behind Mary Jane. The shot switches to Spider-Man beating up the other two guys. When it cuts back to Mary Jane the two windows are intact.
When Peter shoots his web at his bedroom lamp and pulls it across the room, it smashes against the wall and breaks. But when Aunt May is talking to Peter from the door seconds later, the lamp is back on the dresser in one piece.
When Spider-Man is chasing the crook with the gun, the crook shoots 7 times through the roof of the car. Shortly afterwards you can see 9 bullet holes in an overhead shot. As the scene moves along there is another overhead shot (just after Spider-Man jumps the bridge) – no bullet holes. Seconds later the bullet holes return.
In the cafeteria scene, Mary Jane slips on some spilled orange juice that causes Peter to catch her. A short while later when Peter gets up to leave the cafeteria, running away from her enraged boyfriend, the spilled orange juice is not there.
In the scene when our hero, Peter Parker, is chasing the school bus for the first time, the bus stops and it is entirely visible that there is nothing in front of the bus. When the camera is switched to the inside of the bus to show Peter stepping inside to apologize to the bus-driver, however, a tractor-trailer suddenly appears only yards from the front of the bus (visible through the windshield). Some road markings also appear.
When Peter accidentally flings the tray of food on Flash it hits him on the left shoulder but when Flash stands up the stain temporarily jumps over to his right shoulder.
When MJ kisses Peter in the cemetery, his head is leaning towards his left, and in the next shot, his head is leaning towards his right.
At the World Unity Festival, Peter is taking pictures. When he looks up at Harry and M.J. on the balcony, his camera, which has been your average “right handed” camera throughout the film, magically becomes a “left handed” camera. The shot’s obviously been reversed – his parting’s on the wrong side as well.
Near the beginning of the film when we see Peter waking up and reaching for his glasses, in the previous shot he didn’t have the blanket on him or over his shoulders, it’s in the background on the floor, yet when he reaches for his glasses the blanket is on his shoulders.
In the scene after Spider-Man stops the convenient store robbers, it shows a newspaper article. This article virtually repeats itself. Here’s what you can read: “Witnesses claim an unknown masked man was seen exiting the Ling Deli after stopping two suspects from attempting to rob the establishment. Police spokesman John Young said “we’ve heard of Samaritans, but in 20 years I’ve never seen anything like this.” The two suspects were taken to the county jail….(cutoff)….attempting to rob that same establishment. Police spokesman John Young said “we’ve heard of Samaritans, but in 20 years I’ve never seen anything like this.” The two suspects were taken to the county jail.”