Continuity mistake: When Peter falls through the roof and lands in the wrestling ring, the planks on his body suddenly disappear.
Continuity mistake: Inside the school lab, the Lizard walks to Peter on the floor and a stool next to him suddenly appears for him to pick up. (01:35:00)
Continuity mistake: In the car thief scene, the cop points his gun at Spidey and tells him not to move. Spidey puts his arms in the air with his upper arms relatively horizontal and his forearms straight up. But in the immediate shot following, his upper arms are also straight up.
Trivia: Stan Lee makes a cameo appearance as a librarian at Parker's school wearing large headphones, unaware that Spider-Man and the Lizard are battling at the library behind him. (01:37:25)
Continuity mistake: When Peter is looking through his father's file in his bedroom, Uncle Ben comes in and starts playing with a Rubik's cube from Peter's desk. When he sets it down, the top and middle row are red and the bottom row is white. Shortly afterwards, when Peter is researching Doctor Connors on his computer, the top and middle rows are suddenly white and the bottom row is red (not fully solved, as another listed mistake claims).
Continuity mistake: When Peter is told that the thief that killed Uncle Ben has a star tattooed on his left arm, the way the thief steals the money from the cash register is slightly different from the first time we saw him do it. The scene was re-filmed. (00:44:30 - 00:46:40)
Answer: If you're talking about after the dunk scene, Ben didn't see it as Peter standing up for himself. Instead, he says Peter humiliated Flash and then finds out he's the same one that punched Peter earlier. So in Ben's mind, this was retaliation or retribution, which is not OK.
Bishop73