When Ed Helms is in the swimming pool with Anne Hech character he has a large "zit" on his back (right shoulder) - Missing in next scene when he is in the room with her.
When Tim is on the rock-climbing wall, his competitors are alongside him; when Dean Ziegler remarks how high up Tim is (which causes Tim to panic), all of Tim's competitors are suddenly gone.
When the stewardess tells Tim he's in an exit row on the plane, he's sitting in Row 5. Exit rows are never that close to the front of the plane, are always mid-section and/or aft.
When Dean Ziegler first enters the hotel, he yells to the desk staff to stock the mini-bar in his room, which he says is 1019, yet he, Tim and Ronald are staying in Room 112. However, it is possible that at the time Ziegler may not have known that he was being moved to a different room. Ziegler could have also just been saying nonsense just to get attention.
After the awards ceremony, when Ed Helms is telling his boss that he has taken his clients from him, his mouth does not move in sync with the words he is speaking.
The movie starts off in Brown Valley, Wisconsin. However, at the beginning when they're showing different scenes from the town, we see a directional highway sign in one shot that clearly shows a "diamond" shaped state-highway sign, which are used by the state of Michigan (where the movie is filmed).