Continuity mistake: Frank and Tony are talking with Flo and Tony is holding a bong. Through most of the scene, the bong is in Tony's right hand. But in several shots, it switches to his left hand. In one part in fact showing a side angle, Tony has the bong in his left hand and holding it on his leg. It then cuts to a close up and Tony points to Frank with the same but now empty hand.
Picture added by Quantom X