Continuity mistake: The tape is labelled "Vincent Grey" in the first shot, but the label disappears in the next shot.
Character mistake: When Cole and his mother are stuck in traffic due to an pedestrian accident, a cop ignites a flare to place on the road by the car that hit the pedestrian. The police were already on scene, traffic was gridlocked up and down the street, nothing was moving, and he places the flare about 2 feet in front of the car - a move that is unsafe (potential fuel leak) and unnecessary. It would never be done on a city street, and never in heavy traffic.
Trivia: The doctor that treats Cole after the incident at the birthday party is played by director M. Night Shamalyan. Interesting about this scene is that Shamalyan came from a family of doctors, including his wife who is one. He also at one time wanted to become a doctor before he decided on a career in filmmaking.
Trivia: Every time dead people are close by, there is something red in the preceding scene (i.e., when Cole is at the birthday party and is about to get trapped in the attic with the ghosts, there is a red balloon rising toward the ceiling; when Graham comes home to his wife sleeping and is about to realize that he too is dead, she is wearing a red throw; when Cole is in the car with his mother and there is an accident up ahead, she is wearing a red sweater, etc).
Easter egg: On the Collector's Edition Series DVD, go to the Bonus Material menu. Click on the More button, then scroll down to highlight the brown box and press Enter. M. Night Shyamalan will show you a clip of another horror movie he made.