Audio problem: When Harry listens to the recording of Electro's threats to Dr. Ashley Kafka, the sentence is conveniently edited for brevity, omitting part of the original sentence ("A world without mercy"). (01:15:25 - 01:28:40)
Audio problem: During Electro and Spidey's final battle, after Spidey breaks the yellow pipe Electro says "Is that all you've got?" but his lips aren't moving. (01:51:15)
Answer: Peter didn't set out to kill Electro, but he has to stop him somehow. Overloading him is pretty much all Peter has to work with in terms of stopping Electro's rampage. He doesn't know what effect it will have on his opponent, but he hopes that it will serve to stop him in his tracks, which it does. Had Peter set out with the specific intention of killing Max, that would indeed have been wildly out of character, but he didn't - he simply did what he had to do to stop him. It's unlikely that Max is actually dead anyway; it's well known that Sony intend to bring the Sinister Six into play in upcoming movies and Electro has been a key member of most incarnations of that team, making it highly likely that he'll be back.
Tailkinker ★