Conor McGregor's Punch to Heat Mascot Sent Person Inside to Hospital

Conor McGregor punched the Miami Heat's mascot last night, and while it all seemed to be in good (planned) fun ... it actually ended up hurting the dude inside, per a new report.

According to The Athletic ... the man who was playing "Burnie" during Friday's game was sent to the ER after taking a couple of closed-fist dings to the dome ... courtesy of Conor, who was playing along in a clearly orchestrated sketch.

You see, the whole thing was designed to plug CMG's new pain relief spray -- TIDL Sport --which he actually used during the comedy bit. The mascot got socked, went down ... and then got socked again before being dragged away by staffers. Conor was spraying it on the way out.

Unfortunately ... while Conor might've thought Burnie was just hamming it up for the crowd -- the person wearing the costume was legitimately injured. The Athletic says the Burnie dude was treated at the hospital, and then released with pain medication ... and was OK.

So, no real harm or foul all things considered ... and it certainly doesn't sound like anyone in the league or with the Heat is mad at Conor. It's just one of those things -- a battle wound if you will.