The Rae Sremmurd rapper was putting on a show late Friday night at the Union Rooftop in Minneapolis, where he appeared to lose his balance at one point while jamming out to his song, "Black Beatles" ... and promptly fell face-forward into the crowd.

Luckily, it wasn't a hard fall ... and it looks like the security guard standing next to him was quick to reach for him and pull him back up. Swae didn't return the favor though.

Later in the show, the now-shirtless MC held a big bottle of Hennessy above his head ... keeping the party going, and proceeding to take a shot to big cheers. As he passed the bottle back to an audience member, the guard tried intercepting ... and SL wasn't having it.

Swae made sure the guy didn't touch it, and returned the bottle to its presumptive rightful owner. Clearly, the save from earlier didn't mean as much as ya might think.

The good news from all this, though, might be the fact that Swae's stage time here didn't result in something more gruesome or eventful (in a bad way) ... like that time his lip got busted when someone chucked a water bottle at him during a show.