Continuity mistake: 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.
Continuity mistake: When 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.
Continuity mistake: When Norman is getting ready to test himself, he lies down on the bed, fastens himself in and the doctor goes to the computer. However, when it shows him being brought in to the chamber he has several electrodes connected to his chest and head.
Revealing mistake: When Peter Parker first discovers he can climb up walls (while in citizen clothing), he tests it out by climbing up a building in an alley. During this scene, you can clearly see his clothes hanging out forwards, indicating that the scene was filmed with him crawling along a floor horizontally.
Continuity mistake: The scene at Columbia University was filmed on an unseasonably warm spring day, however, the costume department had provided the high school extras with cold-weather clothing. The real Columbia University students can be seen in the background wearing shorts and t-shirts by contrast.
Continuity mistake: In the final battle, the blood on Spider-Man's chin and under his nose keeps disappearing and reappearing.
Continuity mistake: When Spider-Man saves the baby from the burning building, it's amazing that the baby and the blanket are so clean - no soot, smoke damage, charring, etc. The firefighters have obvious soot around their noses from trying to breathe in that area. Did Spidey manage to give the baby a bath before presenting it to momma?
Other mistake: When Jameson is flipping the pictures of Peter's first batch of photographs, you can see (in slow motion or if you have really good vision) that the 3rd picture he looks at changes into an entirely new photograph, when he puts it down. The one he's looking at is Spider-Man on the side of a building, but when it's on the desk it's Spider-Man kicking a thug in the face. The one he then looks at changes too - it was about to have a bit of sky on the left, but then turns into a photo of a street from above, with no sky visible.
Other mistake: When the tram with all the kids is falling, the kids are yelling. The adult behind them isn't yelling & looks bored.
Continuity mistake: When Peter first learns he can climb walls after running out of school, his shoes are different when he is on the wall compared to when he is on the roof.
Continuity mistake: 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.
Continuity mistake: When Peter is drawing up ideas for his costume the hand is that of comic artist Phil Jimenez, current artist of Wonder. Phil Jimenez is right handed and Tobey is left handed. In one of the cuts the pen is in Tobey's left hand but it shows him drawing with his right.
Factual error: When Harry is talking to Mary Jane on the phone, she hangs up on him and his cell phone produces a dial tone. Cell phones do not have a dial tone.
Continuity mistake: During the kiss scene the camera changes view back and forth. From one angle it's raining, in other it is not, then at the end it's pouring as if in a storm. They had to do that scene at least 3 times.
Continuity mistake: During the World Unity Festival, the Green Goblin seeks revenge upon his ex-coworkers. The Goblin throws a pumpkin bomb at them that makes them all disintegrate and disappear. One of his coworkers had a wheelchair with him, which survives the Goblin's bomb and remains on the balcony. (You can see the wheelchair while they are being bombed and after they disintegrate, all in the same shot.) For the rest of the scene, the wheelchair has disappeared from the balcony.
Continuity mistake: 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.
Continuity mistake: When Peter is taking out the trash, and begins talking to Mary Jane, as she walks toward him you can see her underwear sticking out above her pants. As the shots change, this underwear seems to appear and disappear.
Continuity mistake: In the final cemetery sequence, Peter and Mary Jane square off for a little heart to heart, with her touching his face tenderly with her black leather gloves. The camera intercuts between front views of both: in hers, her fingers are touching his ear lobe, in his, they are a inch below his ear lobe. In one quick cut of hers, the hand has disappeared completely, then in mid-sentence as they cut back to Peter, it's there again.
Continuity mistake: During the World Unity Festival when the Goblin attacks, there is a shot of Peter tearing off his shirt exposing a costume that is low cut at the neck. However, in the scene when Spider-Man and Mary Jane kiss in the rain, the costume comes halfway up his neck.
Continuity mistake: When Peter is talking to Mary Jane outside the diner, the same man is seen walking behind Peter 3 or 4 times - biggish man with a flat cap on. First when Peter says "so you're acting now?", then when he talks about Harry not living on earth, then again when Mary Jane walks off.
Continuity mistake: When Peter Parker confronts Uncle Ben's killer in the warehouse, after Parker slams him through the glass windows in the door, the killer drops his gun and pulls out a knife. After he is disarmed of the knife, Peter kicks him up against the wall. At this point the killer has the gun back in his hand.
Continuity mistake: When Peter is talking with Mary Jane outside the diner where she works, watch the positioning of the shadows in the background. As the camera shoots from Peter's point-of-view, the sun is casting shadows up the street. When the shots change to MJ's point-of-view, the shadows are pointing down the street, as if the sun had just moved ahead several hours.
Continuity mistake: During the World Unity Festival, as the balcony first collapses, a blond woman and a man are running to get out of the wreckage. But in the next shot, the same couple just stand under the falling balcony looking up and Peter uses webbing to pull the standing-still couple to safety.
Other mistake: When the cable car is dropping and swinging around, the occupants of the cable car remain standing in the same position. They should have been thrown to the floor when the initial drop was halted, and should have been tossed from side to side in the car as it swung around.
Continuity mistake: In the school cafeteria after Peter saves Mary Jane, he notices the fork that is stuck to his hand. If you look at the back of his hand, the spider bite is gone. In the next scene, it is back again.
Continuity mistake: When 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.
Continuity mistake: When Peter Parker runs into the alley and tests his wall-crawling for the first time, when he runs into the alley the wall he climbs is brick covered with dirty black soot/fungus. After he begins his climb it is completely brown.
Visible crew/equipment: When Spider-Man is rescuing Mary Jane from falling to her death from the balcony, he catches her and spins his web to the balcony to save her and they bungie to just inches from the ground. As they are preparing to bounce back up the shot rotates 90 degrees and you can see the counter weight that pulls them back up coming down to the ground. It's a weird one, this - there's a sound effect as the weight comes into view, so it's meant to be there (or else the sound's just a cover), but it can't be anything he attached his web to, as it was stuck straight onto the balcony. If it's falling, they should be too - his web's not pivoting around anything.
Continuity mistake: When Spider-Man is taking snapshots of the armored car burglary, one of the burglars says "watch the street". As the camera snaps you see them pointing rifles or machine guns towards the sky and when Spider-Man lands on them to dispatch them, the weapons are gone...
Continuity mistake: When Peter and Mary Jane are talking outside the diner, her trechcoat collar is first lying flat, then is tucked in, then is flat. It happens several times when the shot goes back and forth from Peter to Mary Jane.