In real life the Hells Angels would have won that brawl in the Mafia bar

That scene in the movie is pretty far fetched. I know Mob guys are supposed to be tough, but there is little chance that a chubby, middle aged Italian guy can beat a Hells Angel in a straight up fist fight. The Mafia easily intimidates law abiding citizens, but not other criminals. Strip them of their guns, and they lose a lot of their toughness.

Take John Gotti, for example. Can you name a Mafia guy with a more fearsome reputation than him? He insulted a black prisoner in Marion, Illinois in 1996, and the black guy beat him to a pulp. Without his gun, Gotti was practically defenseless against a powerful black man who knows how to use his fists.