There are a lot of plot holes or "what the heck?" moments in this movie (which is why, while I really enjoyed it, I'd still rank it below Homecoming). You can either forgive them and enjoy the movie for its strengths, or knock it down a peg or two for them.
- If every villain was summoned from the moment right before they died fighting Spider-Man, does that mean they'll each get sent back to the moment before they died fighting spider-man? In which case, great, you spent all this time and effort curing them, but they still go back to the moment of their death?
- Why can Ned so easily open magic portals? Anyone upset that Rey could use the force on a storm trooper in Star Wars should be equally annoyed that Ned can accidentally open portals.
- Why didn't Ned continue opening portals to Peter Parker after finding Andrew and Tobey? He finds them and is then all "shucks, we'll never find our guy." Just do it one more time
- How does Happy get through a police cordon to pull in front of his apartment at the end of the big apartment fight? Shouldn't that have been blocked off?
- What exactly *was* sandman's goal in this movie? Sometimes he's siding with Peter to get sent home to his daughter, but then at the end he's fighting against Peter to delay going home?
- As others have mentioned, this "forgetfulness" spell is majorly problematic. Happy appears to remember Spider-Man connected him to Aunt May. But he doesn't recognize Peter Parker. So if he remember Spider-Man connected him to May, why does he think that is? He obviously doesn't remember Spider-man was her ward. Does he think they were roommates and Spider-Man never took off his mask? What? Or what about MJ, will she still remember that Spider-Man was there at the Washington Monument *and* at every stop of the school trip in Europe? If she forgets those things, does everyone else? Does this mean Peter no longer has a social security card or birth record? And yeah, what about all the other universes - does MJ no longer know Tobey's Peter Parker?
It all does detract from the movie for me, but it doesn't ruin it, because everything else was so dang fun.
Thanks and gig'em