Continuity mistake: After Gwen says "I'll be moving to England", she takes a breath, swallows, closes her mouth, but in the next shot her mouth is open. (00:50:40)
Continuity mistake: When Harry at the board meeting sarcastically paraphrases the Connors incident mentioning the "giant lizards" you can see Felicia Hardy in background is writing down things, but she isn't in the previous shot. (00:37:05)
Continuity mistake: At the board meeting, Harry is playing with his father's electronic seal in a way that displays towards the camera the side with the Oscorp logo. But there are two different camera angles from opposite sides, it can't be facing both at the same time. (00:36:55)
Revealing mistake: When Gwen catches Max's elevator in a rush, she clutches to her chest the same mug that when she went through the door was practically horizontal. Luckily it's one of those movie empty mugs people carry for no reason. There's a similar scene the day after when she carries an empty mug - a different one, incidentally - but that's when she is running away from the security and the mug is supposed to be empty. (00:28:20)
Continuity mistake: Gwen's phone call;Spidey holds the plutonium in a different position in each shot - at the end he even just has it standing perfectly vertical on its own. After the first two shots -when his arm goes from behind the grill to under his chin - we are not talking about consecutive shots anymore and the camera cuts away each time for over two seconds so it is technically possible he'd change position every time, but it randomly goes from above the grill, to behind, front, and perched on it. (00:11:25)
Continuity mistake: In the second part of the chase, Sytsevich drives off leaving all the police behind and all the plutonium falls from the rack except the second container from the left in the top row. During Spider-man's antics in the back of the truck you can see the container about to fall (and eventually falling) from the third hole from the left. (00:10:50)
Continuity mistake: Aleksei Sytsevich abruptly stops the truck creating a pile-up of police cars. There's a close-up of a container of plutonium falling off an otherwise full rack, but the following part of the scene shows the rack half empty, and in any case the one contained that fell in the close-up was the bottom left one, in the rest of the scene the one missing from that column is the top left one. (00:10:25)
Continuity mistake: When Spidey wastes 20 seconds of valuable time for the ever important task of fixing Max's combover, he says "Lick that", and in the next shot Max does not lick 'that', but 'the other one'; Spidey put in front of him his left hand but the reverse shot shows Jamie Foxx's tonguing Spidey's right phalanges. (00:10:00)
Continuity mistake: When Aleksei Sytsevich says his own name and cackles, we see the other marauders jumping on the Oscorp truck. There's a shot from a crossroad with a pedestrian wearing a grey suit that looks at the police car in pursuit, and at the street corner there's a woman by the garbage bin; the camera angle changes and the people at that corner have changed. (00:08:10)
Revealing mistake: In the airplane fight, heavy objects (and people) get sucked out of the door once the cabin is depressurizing, but the cables and the mask tubes on Richard's side stay softly curled and unmoving throughout the scene. (00:06:10)
Other mistake: Richard Parker is running away from Oscorp after triggering an alarm at either 6:30 or 9 PM - the movie is contradictory on which one. He goes home to quickly pack and get his son, and then goes to his brother's place to dump him there. The next scene shows him and his wife discussing the situation, including where to spend the night; they are mid-flight to Wisconsin and it's daylight.
Continuity mistake: When Mary and Richard Parker says goodbye to their son, the scene is similar but also different from the previous movie; she delivers her line with a calmer voice and doesn't stroke his hair in the jittery nervous way of the original. The dad's farewell to Peter is also longer and here they touch hands. (00:02:25)
Continuity mistake: When Peter looks at Gwen's mementos, the photo he had in hand and the USB key both change position between shots. (02:07:50)
Continuity mistake: Peter is absent-mindedly listening to the news while Aunt May is putting away some objects. There's a cut while the speaker says "return of the web-slinger" and May who just had put down some letters is suddenly lifting a book. (02:06:25)
Continuity mistake: The one kid Spidey helped is looking at the window during the news story about Rhino breaking out of prison. He leans forward, but he's in a different position between shots, and his wind turbine is powered up only in the last shot even if it was still two shots before. (02:06:15)
Revealing mistake: As he holds the dead Gwen in his arms, Peter says "Stay with me, stay with me" two times, twice, and then a fifth time "You stay with me." Between the two repetitions, you can see Emma Stone's long eyelashes twitch. (02:02:30)
Continuity mistake: In the final battle, Spidey is going hand-to-hand with Goblin while Gwen is still dangling. At one point he wraps his web around Goblin's neck; the two loops of web change distance depending on the camera angle. (02:00:10)
Continuity mistake: When the sickly kid CEO overpowers the two security guards, he does so with the one on the right that mysteriously in one shot is facing him and in the next he's facing the nearby desk, away from him. (01:33:35)
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)
Revealing mistake: Harry Osborn types "Special Projects" (and we see the word taking shape as he types) hitting as the last keys "E", space bar and "G." (01:28:05)
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 ★