Continuity mistake: During the battle between Electro and Spidey, the chip on Electro's head swaps from being on the right side to being on the left. It is specially noticeable when Electro overloads.
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.
Continuity mistake: In the kitchen with his aunt, Peter drinks from a mug. From the opposite angle the arm is lowered.
Continuity mistake: In the scene where the power is out and two planes are on a collision course with each other, the microphone of one of the air traffic controllers changes from a correct position facing his mouth, to an incorrect position hanging way down and away from his mouth, between shots.
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