Other mistake: In the second season episode "The Car Salesman", notice the license plate on the real estate agent's truck. It is the same license plate that is later used in the season 5 episode, "The Ski Lift".
Ted and Mary - S1-E2
Other mistake: There are multiple mistakes with the bowling scene in the beginning of the episode. Firstly, Mary is shown finishing her game with a strike. After she strikes she goes back to the table where Ted, Larry, and his wife are sitting. The scores are shown and Ted and Larry say that Larry needs a spare to win. In the scores it shows that Mary's last shot was actually an 8 and not a strike that she had finished with. Secondly, Mary had finished with a 140. Larry's score shows that he has a 120 in the 9th frame, with a strike in his first shot of the 10th frame and a 7 on his second shot. Regardless of whether or not Larry completes his spare, he would not have won, as his max score could only be 140, so he would have tied Mary. And lastly, when Larry goes up to complete his spare which should have had 3 pins remaining, there is a full rack of pins and Larry gets a strike. After his shot it is implied he won the match, even though the scores showed that it was impossible for him to have won. (00:00:10 - 00:01:00)
Other mistake: Larry and Jeff are sitting, talking and having coffee. Their coffee is in styrofoam cups with plastic lids. Both Larry and Jeff sip from their cups but the lids are closed not open to allow sips. (00:10:14)
