Continuity mistake: In the final golf scene at the 18th hole, the media tower falls in front of Happy's ball. When he decides to use the tower to help his ball go in the hole, watch the heads of the members of the audience. Happy hits his ball and the members of the audience are watching the ball and following it as it makes its way down the tower. It is natural that their heads will go left, right and down as they follow the ball. However, a few times, it is shown that their heads even go up, as if they are following the ball upwards. Clearly nothing can naturally move up on its own. Plus, it's only shown that the ball is going down, or to the sides.
Continuity mistake: When there is the small explosion when the car hits the radio/satellite tower, you can tell that it was filmed after the car itself crashed. The car was positioned, and the explosion was set off, so there is no movement in the car, even though it should still be shaking from the impact.
Continuity mistake: At the 18th hole when the television tower collapses you can see a man in an orange t-shirt and jeans jump off onto the floor. However in the next shot (it is quite quick so you might have to watch carefully) the same man is just jumping off and is still in the air rather than on the floor. (01:23:35)
Continuity mistake: During the final golf tournament it is obvious that some scenes were shown out of order. When Happy tells Shooter "Somebody learned how to putt," he's wearing the Subway shirt. A couple of shots later he's wearing a blue golf shirt. A little bit later the announcer says that it is the end of day 1, so I doubt he would have changed his clothing in the middle of the day. Also, when it is supposed to be the next day, he's wearing the Subway shirt again.
Continuity mistake: At Happy's first tournament (the one he goes to with Chubbs), when Chubbs does the 'it's all in the hips' motion there is a lake behind him and Happy. However, when Happy then hits his ball and we see the overhead shot from the ball's point of view, we can see that there's no lake anywhere near them - it's just a green fairway.