Continuity mistake: When we see Spider-Man protect the armoured car and take out the thieves, we see that Spider-Man throws a robber over his head and the robber hits a wall. The following shot his position has changed lying on the floor. (00:58:35)
Continuity mistake: When Jameson is flipping the pictures of Peter's first batch of photographs, you can see that the 3rd picture he looks at changes into an entirely new photograph, when he puts it down. The one he's looking at is Spider-Man on the side of a building, but when it's on the desk it's Spider-Man kicking a thug in the face. The one he then looks at changes too - it was about to have a bit of sky on the left, but then turns into a photo of a street from above, with no sky visible. (00:58:45)
Continuity mistake: When Peter leaves Jameson's office after becoming a freelancer for him, Jameson closes the door, and at the end of the shot, the door is half-shut, but in the next shot, the door is completely shut. (00:58:45)
Continuity mistake: In the film Norman Osborn is talking to the board of the company where they announce they are selling the company. In one shot if you look on the table most of the folders that the board are holding are open. In the following shot most of them are closed. (01:00:30)
Continuity mistake: At the start of the Unity Festival scene just after we see Peter taking a picture, it cuts to Macy Gray, in the first shot she is not holding onto the mic stand, yet in the following shot she is. (01:02:00)
Continuity mistake: At the World Unity Festival, Peter is taking pictures. When he looks up at Harry and M.J. on the balcony, his camera, which has been your average "right handed" camera throughout the film, magically becomes a "left handed" camera. The shot's obviously been reversed - his parting's on the wrong side as well. (01:02:10)
Continuity mistake: At the Unity Festival, when the Green Goblin flies past on the glider, the camera cuts to a shot of the balcony, and behind Harry and MJ there is a man in a black suit that takes a picture (you can see the flash from the camera). But when the camera cuts to a close up, the camera that was in his right hand has vanished and is now a glass of wine. (01:03:40)
Continuity mistake: During the World Unity Festival, as the balcony first collapses, a blond woman and a man are running to get out of the wreckage. But in the next shot, the same couple just stand under the falling balcony looking up and Peter uses webbing to pull the standing-still couple to safety. (01:04:15)
Continuity mistake: In the big carnival scene when the Green Goblin has thrown a bomb at the balcony the shot cuts to Peter and he sees two people about to get crushed by a falling rock. You can see that they are facing Peter with the woman on the right and the man on the left. The shot changes and they have their backs to Peter and the woman is now on the left, the man on the right. (01:04:15)
Continuity mistake: During the World Unity Festival, the Green Goblin seeks revenge upon his ex-coworkers. The Goblin throws a pumpkin bomb at them that makes them all disintegrate and disappear. One of his coworkers had a wheelchair with him, which survives the Goblin's bomb and remains on the balcony. (You can see the wheelchair while they are being bombed and after they disintegrate, all in the same shot.) For the rest of the scene, the wheelchair has disappeared from the balcony. (01:04:45)
Continuity mistake: At the World Festival, Goblin is beating up the cops; however, when Spider-man tries to punch him, there is a long shot where you can see that there aren't any police anywhere. (01:05:30)
Continuity mistake: In the unity festival scene when the Green Goblin starts shooting at Spider-Man, he is about to run past the silver pushcart with an umbrella, yet when it cuts to a view from the Green Goblin, Spider-Man is quite some distance from that pushcart. (01:05:50)
Continuity mistake: When Spider-Man catches Mary Jane as she falls off the balcony, in the shot from above there are two columns lying on the ground - one on the right as we look at it, a few feet from the red area and parallel to it, and one on the left at an angle. In the shot of them landing, the one closest to the red area has disappeared. (01:06:50)
Continuity mistake: When the part of the balcony where Mary-Jane is starts to break, there's a lamp on it. It vanishes the following shot, then reappears some shots later. (01:07:05)
Continuity mistake: There's a purple tent below and to the right of where MJ is trapped on the breaking ledge. When the Goblin is kicked off of his glider by Spider-Man, he falls to MJ's left but lands in the tent on the right. (01:07:45)
Continuity mistake: While Peter is talking to Mr Jameson in his office around the middle of the film, he picks up the phone and calls in one of his assistants. When he suddenly appears at the door he moves the phone away from his ear twice. (01:11:25)
Continuity mistake: In the scene in Jameson's office after he throws his cigar out the window and the Goblin throws it back, when Jameson is looking at the cigar on his desk, he is sitting at an angle. Right before the Goblin crashes in, Jameson is sitting perfectly straight at the desk, with both hands on the desktop. (01:11:50)
Continuity mistake: When Norman Osborn finds out he is the green goblin from his mirror reflection, watch closely at his hair in the reflection and the real him, his hair in his reflection has a thick strand of hair hanging over his fringe, and the actual him, has his hair without any parts hanging over his fringe. It changes about three quarters of the way through the scene. (01:13:35)
Continuity mistake: In the scene where Spider-Man wakes up after being gassed by Green Goblin, when Green Goblin puts his hand on Spider-Man, it's in a different position on his face in the following shot. (01:13:50)
Continuity mistake: In Jameson's office you can see a building across the street through the window, but when Spider-Man is gassed and falls out, a shot from the street shows Spider-Man falling from an extremely high building that has no other buildings near it. (01:14:25)
Answer: Remember that Green Goblin (Norman Osborne) just found out that Peter Parker is Spider-Man. Aunt May's comment about everyone knows he loves Mary-Jane concerns him because he now realizes that Green Goblin might find/kidnap Mary-Jane just to lure Spider-Man into a fight. This is the basis for the whole reason he can't be with her, as he would be potentially putting her in harm's way all the time if they got together.
Jazetopher