When Maggie sees the truck she is about to hit towards the end of the movie, the truck is coming from the right side of the road and making a right turn. Later on when Nicolas Cage comes around to where Maggie is lying, the truck position is in the opposite direction, like it came from the left side of the road.
Maggie wakes up in bed wearing a ribbed tank top. She rolls over to check the time on the clock and suddenly she's wearing a satin spaghetti-strap camisole.
When Seth is cutting the lettuce, he pulls a knife out of the knife block containing 4 or 5 knives. In a later shot, after he has cut his hand, there is only one knife in the block.
When Maggie is in the bathtub, Seth can clearly be seen in the corner of the mirror when Maggie runs her hand through her hair. Then in the next shot (the famous 'no-reflection' scene), he has no reflection.
When Maggie is riding her bike to the hospital at the beginning of the movie, the seat is clearly adjusted quite high. When she parks the bike, the close-up of the bike shows the seat only about two inches above minimum.
When Maggie and Seth are looking at Maggie's blood through a microscope, the image shown is too zoomed in for a light microscope (with a maximum resolving power of around X1500).
Maggie enters the public restroom of the hospital to vomit. The angle from behind the toilet shows marble bathroom stall walls and balloon curtains on the windows. This scene was obviously filmed in the public restroom of either an upscale hotel or restaurant, not a hospital.
When Maggie is performing surgery she says her patient to stick alive to give her Seth number. Seth looks like it's a new, but he's supposed to read her mind, he should already knew she was after him before her to say a word.
At Messinger's welcome home picnic, Seth's reflection is visible in the sliding glass door. But Seth can be seen if he wants to be.
Although Seth is a physically invulnerable angel, having never been a mortal human being, his skin is visibly scarred.
The rooftop basketball goal is at the corner of the helicopter landing pad where it could come in contact with a rotor.
When Maggie and Jordan are talking in the locker room and Jordan ask her to marry him, you can see his mouth move, several times, when the camera is behind him, but he doesn't speak in the scenes with the camera behind him.
When Meg Ryan listens to Dennis Franz's heart with her stethoscope, she places the stethoscope in her ears backwards. (Ear canals angle forward and stethoscopes do likewise - putting them in backwards is painful and can also prevent them from working) Ouch!
When Maggie and Nathaniel Messinger had their first meeting she pronounces his name as Messenger, to which Nathan's wife replies that she should pronounce his name properly and later on Maggie does that, by calling Messinguer. However, Nathan himself and in front of his wife says Messenger as his surname and he isn't corrected at all in future scenes.