In the scene with Happy and the four other golfers(gold jacket guys), when the guy says he heard about the hole in one on a par four, Shooter takes a sip of his drink. Right away they cut to Happy, and Shooter takes a drink in less time than it would normally take to get another drink. Plus, the glass stays the same level.
It was supposed to be the director's idea of a smooth shot transition. He's raising his glass, then he drinks in the next. Unfortunately he drank in both shots. The BIG mistake here is not necessarily the two drinks, but the fact that it's in his other hand when they show happy, then back to normal in the group shot.