The scene in the back of Tony's bar when Charlie is haranguing Johnny Boy about paying his debts, and they're talking about the girls "Is she the one on my left, or your left" will never be surpassed.
I think DeNiro and Keitel did a little tribute to their Mean Street banter in Irishman. When Bruno asks Sheeran if he knows who else owns a piece of the laundry service and Sheeran says he doesn't know, then Bruno says he does. Sheeran says something like "oh, you know who?" and Bruno replies, "No, I do, as in I own the place". lol. That was right out of Mean Streets. Actually reminded of the "we're both staring the same direction" line.