Continuity mistake: When John Jameson and Mary Jane are walking down the stairs during John's celebration party, there are two people halfway down the staircase standing by themselves. When it does the closeup of John and Mary Jane, there are four people now standing in that spot.
Factual error: The only elevated trains in Manhattan are Metro North that goes to Connecticut and the N, Q, R, W line that goes to Brooklyn/Queens, and that line goes over a bridge. None of these trains are elevated in mid-Manhattan; and most certainly, the end of the subway line would not just be a big metal "bumper" that leads into the water.
Other mistake: The Spider-Man outfit that Peter throws in the trash appears to either have the head attached to the body or a very long neck on the mask. It hangs too far down over the edge of trash can to be the same, separate headpiece, with a short neck, that Jameson receives from the trash collector. (Though this may be a deliberate nod to the comic book, it is still a mistake.)
Factual error: Harry stumbles onto his dad's secret room and it is free of dust except for a few cobwebs. While there may have been no human activity in the room for almost two years, there were holes in the room that let sunlight, air, and insects/arachnids in, therefore there must have been airflow. With the airflow, dust or dirt should have entered the room and collected on the items.
Continuity mistake: In the first few shots of Mary Jane held hostage by Dr. Octopus in the factory, her arms above her head change from straight to bent and back.
Visible crew/equipment: Boom mic reflected on upper part of phone when Peter puts a 50 cent coin in.
Revealing mistake: When Dr. Ock abducts Mary Jane he is replaced by a lame CGI figure.
Character mistake: In the start of the film, the sticker on Peter's head for his work misspells the word Bleecker Street on it.
Continuity mistake: In the train scene, Spider-Man is thrown through a window and the fight continues over the broken window. When a train is coming from the opposite direction, Spider-Man leans over to avoid it, and the window isn't broken anymore.
Visible crew/equipment: When Peter rides his motorbike, in the wide shots he's replaced by an obvious stunt double who wears safety goggles.
Continuity mistake: When the car crashes in the cafe, it crashes against a column on the left. In subsequent shots the column has no damage at all.
Continuity mistake: Mary Jane holds the wedding card with her left hand. A frame later she is holding it with her right hand.
Continuity mistake: When Peter asks Mary if she wants some chop-suey, the same cab passes behind her twice.
Visible crew/equipment: Film crew and boom mic reflected on lower left glass of cafe when Dr. Ock approaches.
Continuity mistake: In the bank, a desk filled with papers zooms towards Dr. Ock. The papers fly away, but reappear a frame later when he tears the table apart.
Continuity mistake: Spidey and Octopus fight at the tower and a huge chunk of concrete falls on the street below. Seconds later, however, cars are seen moving around, no honks, no crashes, no problems at all, as if the falling rubble had simply vanished.
Continuity mistake: When Spider-Man stops the train his head and chest fall forward due to the momentum, but a frame later - from a different angle - he is standing still, his body against the train structure.
Deliberate mistake: Perhaps to avoid getting an R rating or parental complaints notice how in the operating room massacre none of the doctors appear to bleed nor do Doc Ock's tentacles have blood on them.
Suggested correction: The problem is in both versions of the film, basically all of the deaths either happen off-camera, or are things like people being shocked to death or killed by being tossed around and presumably having their backs/necks broken. Most of the deaths would be bloodless or near-bloodless anyways, and the camera simply doesn't linger on the bodies enough to show any blood. This is also why the tentacles aren't really bloody. Sure, it was probably ratings-related, but it isn't technically a mistake.
Other mistake: During the hospital scene where the robotic arms kill all the operating room staff, we see 4 different camera angles on the last doctor to be killed. All the arms have cameras in them, and show his face screaming at 4 different angles. Yet it should only be 3 as one arm has its claw wrapped around his neck. And it doesn't release from him, as it can be seen still wrapped around his neck by the other 3 cameras in each claw.
Visible crew/equipment: The camera and a boom mic are visible in the police car lights in the scene directly following the first accident with Doc Ock.
Suggested correction: Jameson must have tucked the neck up inside the mask so it would hang correctly on the wall. If he hadn't, the extra material would have bunched up under the chin area and pushed the face upward. Jameson clearly wanted the mask to "look" straight ahead.
Phixius ★
This entry isn't about how Spider-Man's costume was hung up on Jameson's wall. It's about how the mask was attached to the body portion of the suit when Peter threw it in the trash.