Revealing mistake: When the couple split the pole, they get hit by a bus. As the shot cuts to a wide shot, you can see the couple have been replaced by dummies, just before the bus hits them. (00:10:20)
Revealing mistake: When Cindy drives down the road, singing along with the radio, depending on the shot, the roadside differs. In closeups of Cindy in the car, she drives past trees/bushes, yet in wideshots there are no trees or bushes by the roadside. (00:13:35)
Revealing mistake: At the beginning, when the girl is driving down the road, there are leaves on the ground, but the leaves in the trees look green. Passing one of the bushes on the road, the leaves are blowing from directly behind the bushes, where a fan must be hiding. (00:14:15)
Revealing mistake: In the shot where Cindy drops her bag of clothes, toothbrushes, etc. You can see that the clothes and things fall from above when they should've just fallen from the bag. (00:16:45)
Revealing mistake: When the guy with the weird hand is serving dinner, you can clealy see through the cuff on his left arm that his real hand is there. (00:24:50)
Revealing mistake: When the ghost starts having oral sex with Tori Spelling, you can see her tongue moving to make the cheek motions. (00:30:45)
Revealing mistake: When Tori Spelling is looking for Hugh in the shot where the chandelier falls on her, if you pause it in the right place it is painfully obvious she has been replaced by a dummy. (00:53:20)
Revealing mistake: When Cindy and Buddy get trapped inside the cold chamber, she starts rubbing him to a point that it becomes masturbation. But when she's sitting on his legs doing the thing, in one side shot you can clearly see she is not holding his privates and her hand is just going up and down, closed but empty. (00:58:05)
Revealing mistake: When Dwight flies into the banister in his wheelchair, after colliding with Hugh, from a back shot you can see marks made previously in the wood to make the banister break in those parts, more easily. (00:58:45)
Revealing mistake: In the wheelchair duel, you can see that Dwight is "burning rubber" with his wheelchair, but the wheels are not moving. (01:00:30)
Answer: I want to know this so badly as well and can't find it. The Graduation Song is not right.