Deliberate mistake: Wade and Quinn go to the Top Hat Club. We see a line of people waiting to get in. After they are in the club a while, leave in a taxi, go to the park to meet Rembrandt and Arturo, discuss some things, talk to some passersby, and go back to the Top Hat. We again see a line waiting to get in. It is the same line with the same people in the same place as way earlier. It is a repeated shot of the previous queue from when they went there the first time.
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)
Answer: The show's creator admitted that it was the wrong Arturo.