Greatfellas - S2-E10
Deliberate mistake: When Quinn comes back to the hotel room with a large stack of money he'd won at the casino, he waves it, and you can see a 1-dollar bill in the middle. He was supposed to have over $100,000, but since the crew couldn't get that much money for a brief scene, they used a stack of dollar bills. (00:35:40)
Chosen answer: Quinn's brother was going to be a recurring character, so "introduced" in this case referred to the actor becoming a semi-regular.
Jean G