Continuity mistake: Peter is cooped up in the garage window as he answers the phone after a night of dangerous experiments. First shot and his arms are free, close-up, and he's wrapped in a blanket. (01:05:00)
Continuity mistake: Harry just found by accident the secret interactive desktop from his father. He drags and drops a menu, but somehow when he checks out the item he highlighted, the menus themselves changed entirely showing stuff like "Max Dillon experiment" that were not there a moment before. (01:03:05)
Other mistake: We see Peter freshly printing an old news story from CNN; the timestamp on the visible corner says the sheet was printed at 9:18 AM. The scene takes place in the evening. (01:01:45)
Continuity mistake: Watching the news after his confrontation with Electro, Spiderman picks up from the table the webbing device that got fried. He then throws it back on the table, where meanwhile all the tools shifted around randomly. (01:00:40)
Revealing mistake: Look behind the policeman when he shouts "Sir, get your hands away from the cables, right now." For absolutely no reason the extras (one in particular to the left that was looking in a different direction entirely) remembers to act scared only at the word "get", but the policeman already started shouting before, and sparks have been flying even earlier. (00:52:00)
Continuity mistake: A policeman spots the suspicious guy accessing the high voltage cables and screams "Get out of the way." There's a macroscopical continuity error here with an extra sporting a peach colored jacket that 'gets out of the way' twice in two separate shots and with completely different timing. (00:52:00)
Other mistake: Car alarms are annoying; Electro sets off every car alarm in the street, once he silences a single one draining power off the batter, every other alarm stops too - despite the lights still flashing. Incidentally, in the rest of the movie Electro shows his power on a much larger scale but never sets off any car alarm or makes headlights blink. (00:48:35)
Continuity mistake: Peter and Gwen are having a spontaneous reunion. Gwen tried her new laugh on Peter, and she's laughing at his positive reception of it saying "It's not adorable." Notice by her a dude with thin framed glasses and a beige jacket that walks past them. A few seconds later when she does the nose rub thingy, the same guy is again passing them by. (00:47:15)
Continuity mistake: Playing with stones by the river (the GPS coordinates on scree are a perfect match for Pebble beach), Harry says "I tried to forget everything about this place." Peter is scratching his chin, but in the next shot his hand is nowhere near his face or even in frame. (00:42:05)
Continuity mistake: The two friends are chatting from opposite sides of the riverside railing. Peter says "Yeah"; look at the folded hat in his pocket. Next shot, he adds "I don't know" and the cloth is wrapped in a different way than before. (00:41:30)
Continuity mistake: Harry Osborn says at the business meeting that everyone will work for Felicia; Felicia's hand position in close-up is egregiously different from the one she has in the view of the table. (00:38:30)
Continuity mistake: At the meeting, Harry says "What was Dad thinking?" The lawyer with the purple bowtie is looking at him, hands off the table, but in the next shot he has both hands on it. Same a few seconds later when Harry says "Hi" to Felicia; hands on the table first, off the table in the reverse angle. (00:37:35)
Other mistake: When Max picks up the blueprints scattered in the street, behind him lingers the view of a building with the banner for the 2013 NFL Draft, including fully visible the date "April 25-27." Since it happens on graduation day for Peter, it'd have to be an ad a month or two old...and a year old, because it's established that the movie takes place in 2014. (00:09:25)
Continuity mistake: When Max holds the cables and sings happy birthday to himself, the position of his left-hand changes, from more distant to the ring of the connector in the view from underneath, and closer to it in the other angle. (00:36:10)
Continuity mistake: When Max is talking to his boss and fantasizes to assault him, there's a woman walking past them reading some documents, and she keeps coming from the corridor and passing them by - that's without considering Max's fantasy, just shots of the 'real' events. (00:27:50)
Deliberate mistake: When Spidey jumps on the hood of the truck, Rhino squirts him using the wipers. Funny, but he can do that only because the detergent sprays forward instead of the angle actual windscreen washers are pointed at. (00:12:50)
Other mistake: We see a good view of Spiderman's suit during his acrobatics in the air at the beginning of the movie; it's skin-tight and has no compartment or belt. However, when Gwen calls, Spidey reaches behind his back and pulls his phone out. (00:11:30)
Other mistake: This movie is set in 2014 (obituary of Norman Osborn) and Peter's parents disappeared in 2002 (articles printed by Peter, FBI files), but in the first movie the young version of the protagonist was credited as " Peter Parker (age 4). " Peter Parker is not supposed to be a 16 years old boy in this movie which opens with his graduation.
Other mistake: The first shot of the movie is an ominous zoom-out from Richard Parker's watch, a top quality Swiss watch...although, it shows that it's 5:42, and the timestamp in the security cameras is 21:05. (00:00:55 - 00:01:25)
Continuity mistake: When the kid slowly hobbles towards Rhino somehow outsprinting all the policemen, seen from behind he is walking in the shade for a large tract, but the street is sunlit in the other views. In general throughout the scene the police cars are now in the shade, now in the sun. (02:10:30)
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