When Donny and Robert kidnap Ted, he escapes into the bathroom to call John for help. He calls from a land-line phone. Donny ends the call by disconnecting the telephone wire from the wall, yet there is a dial tone. A land-line phone would go completely silent once its cord became disconnected.
When Ted is escaping from Donny's house, Donny is dancing in front of the TV while sipping a soda. The camera switches to show Ted running by the door, and suddenly Donny is dancing with his hands on his hips, and there's no glass of soda to be seen.
The Jetta's hood is pushed in after it crashes into the Volvo. When the Jetta comes to a stop outside Fenway Park, the hood is fine apart from the license plate hanging loose and some dirt on the grill.
When Ted and John sit in the park and attempt to smoke pot, the bench is right next to a tree trunk. After Donny and his son approach them, they are sitting on the same bench, which is now several feet to the left of the tree trunk.
When Rex goes to talk to Lori at her office desk, his hair is combed back. In the next shot, his hair is a different style with more camera light. In the next shot, it's back to the original combed back look with darker camera lighting.
The supermarket where Ted works is supposed to be in Boston, but the reusable tote bags for sale at the register are from Best Yet Market, which is only in the New York City area. It's also different from the store on the cashiers' name tags.
When John and Lori arrive at Donny's house in Chelsea to rescue Ted, they drive the wrong way on Chestnut Street (a one-way street). Donny leaves, with Lori and John following, going the wrong way on Pine St. (also a one-way street).
Near the end of the movie, the characters are able to sneak into Fenway Park with little difficulty due to a garage door being partially left open. This obviously would not be the case in real life. Also, with no baseball game going on and no cleaning crew visible, the stadium lights would not be left on for no reason.
Lori manages to find John at Ted's home warming party, but John didn't tell her the address. Ted finds the hotel John was staying at after Lori dumped him, even though John didn't tell him where he was.
Ted is a living teddy bear, unlike any other in the world. While the film proposes that eventually his novelty wore off and that he ran through the money he made at the height of his fame, it never explains how or why there wouldn't have been endless interest in Ted and thus an endless source of income for him.
In fact, the film goes out of its way to demonstrate that Ted is still quite well- known throughout the film and yet for some reason he still needs to get a job and earn a living.
During John and Lori's anniversary dinner at the restaurant, after John says "Let's just enjoy our anniversary dinner", the view of the street outside is clearly waving, as if it were a printed on a canvas and made to look like the outside of the restaurant.