12th Feb 2015
The One With Joey's Porsche - S6-E5
Revealing mistake: The triplets are supposed to be two girls and a boy; however, certain revealing shots of their anatomy when they are in Monica's apartment show that the two babies playing the girls are actually boys.
1st Oct 2014
Continuity mistake: When Lt. Roberts is held hostage in Admiral Chegwidden's office with the Admiral and the Major, he mentions a sister named Winifred. She is never mentioned again throughout the series. In later seasons it is implied that Lt. Roberts only has one sibling, a brother named Mikey.
23rd Oct 2012
Other mistake: The signature on the copy of the Silence Dogood letter is different than the one on the original. They should be the same if it was truly a scan.