The One With The Chicken Pox - S2-E23
Factual error: The symptoms (spots, fever, etc) of chicken pox only develop 2 - 3 weeks after exposure to the virus. Therefore, when Ross knew that Ben had chicken pox, Phoebe shouldn't have developed the condition until at least two weeks later, and Ryan certainly shouldn't have developed the disease until the end of his stay (as Phoebe was his only contact with the virus). (00:09:30)
The One With the Baby on the Bus - S2-E6
Factual error: In the one where Joey and Chandler lose baby Ben on a transit city bus, they later have to pick him up at the transit city headquarters. The man working there assumes that one of them is the father. There is no way that a city official would just give away a baby without checking for ID or a birth certificate or proof of fathership of the child. (00:14:30)
The One With The Chicken Pox - S2-E23
Factual error: Ryan is a LCDR submariner, who had been on a sub deployment for the last two years. but at no time does he wear his dolphins pin. A true submariner would sooner forget his skivvies than his pin.
Answer: Usually by the seventh night of Hanukkah you don't know what to get the other person, and you will probably resort to getting the other person something insignificant. Chandler is basically saying that the pen is a stupid gift.