Continuity mistake: Spider-Man leaves the "I love you" message to Gwen on Brooklyn Bridge, and on the tower of the bridge you can see the American flag. When the bridge is in the background later, the flag is gone. (01:45:15)
Continuity mistake: When Electro pierces the chest of the head of the security, the guy falls at a certain distance from the chair and table of the office, but when Harry saunters off to his body to grab his gun, the dead guy is right by the furniture. (01:40:05)
Revealing mistake: Max is having a delusional monologue at the mirror with his imaginary friend. You can notice that the 'gap' between his teeth is represented by a piece of black tape. (00:24:30)
Continuity mistake: When Peter pulls the boot of the costume under the cover to prevent May from seeing it, you can get a good look at the stack of books he's going to trip into a few seconds later. In fact, you can still see even as he trips, that the stack includes the famous leather bag from his father. He doesn't knock it to the floor when he trips, but the next shot just shows it on the floor anyway. (00:23:25)
Continuity mistake: The little bullies are pushing the wind turbine kid against the fence; they literally have their fingers inside the links; they look up and notice Spidey, barely move very slowly, but a moment later they are much further back in the alley giving him a solid few meters of space where he lands. (00:20:35)
Continuity mistake: Coming out of the Chinese restaurant, Emma Stone is closing her coat, and you can see in the view from behind that she even completes the movements to properly tie the belt. The scene continues, the belt is perfectly fitting and closed, but the last shot of the scene shows Gwen Stacy in front of the door with the coat open and the belt loose. (00:17:35)
Continuity mistake: When Peter is kissing Gwen by the podium, Garfield's right hand is on Emma Stone's cheek, but in the reverse angle his hand is on the middle of her back. (00:14:35)
Continuity mistake: The very first time we see Max Dillon, he's carrying literal blueprints around. He mumbles "There's more room on the sidewalk"; notice behind him just after he says "Excuse me", a man with white hair and beard, smartly dressed with a handkerchief in his breast pocket. The shot changes and the same extra is coming from the opposite direction in front of Jamie Foxx. (00:09:15)
Continuity mistake: In the opening scene, Richard Parker hears his son Peter calling his name, and he rushes to check on him, opening the door to his study who has been ransacked by someone. That's the same scene as the first movie, only it is absolutely not the same; not only the position of the items in the room is different (and so also the lighting, since lamps were amongst those objects) but Campbell Scott opens the door using both hands instead of just his left (check out the same timecode of the first movie). (00:02:10)
Revealing mistake: During the "Gone Gone Gone" montage where Peter recaps the parents subplot by plastering his room with various junk about them, he sticks a particular newspaper clipping using tape. The article is an obvious movie prop fake; look at the right of the photo and you can see the paragraph begins with not even a proper sentence; "Cell regeneration, and long time partner and friend to Norman Osborn, went missing", which is the copy and paste from the beginning of the article save the first line. Copy-paste can also easily be spotted from the leftmost to the rightmost column. (01:01:50)
Continuity mistake: Spider-Man launches Electro against some metal towers and says "your muscles, bones..." and starts to stand-up, left leg extended. Shot changes and he is kneeling. (01:52:15)
Continuity mistake: When Electro's face appears on the building's windows, he produces huge holes on the pavement, which is empty except for a police car. After Spider stops by the water tank the aerial shot shows the street jammed with cars. (01:49:25)
Continuity mistake: After the blackout when the plane lifts up, Gwen is standing next to Spider-Man, with her left hand on his back. She is just 20cm smaller than him. When the shot changes she is now standing away from him and he is 40cm taller. This changes back and forth. (01:47:25)
Continuity mistake: When Peter is home watching the news, he grabs his cell phone and places his thumb on the screen. In the close-up it's away. This swaps back and forth. (01:00:35)
Continuity mistake: When Peter spots Gwen on the street he stops a truck that stops 20 cm away from him. When the angle changes the truck is further back. (00:45:40)
Continuity mistake: When Harry and Peter talk by the river they're alone in the wide shot, but with a couple to the right in the close-up angle.
Revealing mistake: During the plutonium heist, when the truck skids, tire marks from previous takes are visible on the pavement. (00:10:20)
Continuity mistake: After Spidey fixes Sam's hair he puts his hands on his ears. When the angle changes the hands are gone. (00:10:05)
Continuity mistake: When Rhino walks towards the cops he is a meter away from two cars. From the aerial angle he is 10 meters behind, moving towards the cars again. (02:09:50)
Continuity mistake: Before Peter googles Roosevelt he drops stuff on the floor. The position of the objects changes drastically between shots. (01:01:20)
Answer: Peter could have webbed him up and called the police anonymously.
MasterOfAll
Very likely. However, there was a deleted scene in which Peter, out of anger over Gwen's death, almost beats Harry to death.
Yes. We also see Goblin getting knocked out when all hell breaks loose, and the gears all break apart. Chances are, Peter just webbed him up. (Although, as the other response says, he also got beaten up in a deleted scene.)
TedStixon