Michael Pena's 'End of Watch' Fight Compared to Viral Clip of Cop Brawl

Michael Pena might be getting flashbacks watching this ... a cop throwing hands with an unarmed civilian, and losing his own gear to get on equal footing.

Check out this wild fight between a police officer and a regular schmoe from the streets ... where they both decide to square up and duke out whatever issue they're having. It's pretty nuts -- the cop actually takes off his vest (but still keeps his gun) to throw down properly.

They exchange minor blows for a good while, with the cop seeming to have the upper hand -- he's way bigger for starters -- and the dude in green coming back for more each round.

In the end, they appear to leave their differences right there on the pavement ... seemingly without further incident. Of course, many have pointed out that this doesn't look to have happened in the States -- where a civilian would surely be busted for scrapping with a cop.

Of course, the other observation here ... this is very much like a scene from the 2012 movie "End of Watch," in which both Pena and Jake Gyllenhaal star ... where they play wayward cops. At one point in the flick -- Pena's character, Mike Zavala, brawls with a perp.