Revealing mistake: As Mac says "I'm very worried about these guys" and exits the bar, there's a shot right through the door and it's not the bar inside at all, just a wall with some pictures on it, much closer to the door than it should be.
The Gang Wins the Big Game - S13-E9
Continuity mistake: When Uncle Jack is filming Bill drink a beer, he is holding it horizontally. When the shot cuts to what the phone sees, the video is shot vertically. When it cuts back to Jack, he's still holding it horizontally. (00:01:06)
Time's Up for the Gang - S13-E4
Continuity mistake: After Dennis concludes with his presentation, everyone stands up, including Dee. In the next shot, everybody but Dee is standing and Dee is now getting up again. (00:19:24)