* DawsonCasting: This is averted with the young actors playing Tommy's children, but an unusual example seems to take place when when Jerry Adler joins the cast in season 4 at the age of 78; his character is an elderly man, but since he still works a regular shift in a firehouse he realistically must be much younger than the actor playing him.
* IAmNotSpock: Callie Thorne, Sheila Keefe's actress, mentioned in an interview that fans act wary when they meet her, expecting her to be as crazy as the character she plays.