The Boston Red Sox World Series celebration just took a major hit at the championship parade on Wednesday ... after a rogue beer took out part of the Commissioner's Trophy!!

Boston fans let the beers fly through the air at the team's World Series parade ... and players caught and CHUGGED them.

But, one fan missed their target and hit the championship hardware right in one of the flags ... denting it pretty badly. The trophy was riding with Mookie Betts at the time.

That's not all ... one fan threw an open beer at manager Alex Cora ... and the dude was clearly PISSED, stopping his duck boat to point out the potential culprit.

One man was arrested and charged with assault and battery by means of a dangerous weapon, minor in possession of alcohol and disorderly conduct after throwing an unopened beer can at a boat for the hit on Cora.

Overall, there were 6 total arrests during the parade.

It wasn't all bad for the Sox, tho ... guys like Blake Swihart, Matt Barnes, Craig Kimbrel and Rick Porcello were able to snag cans out of mid-air without incident ... and you better believe they didn't let them go to waste.

This ain't nothin' new for fans in New England -- Rob Gronkowski famously did the same thing (while wearing a Minions hat) when the Patriots won it all in 2015.

What else would you expect from the world champs??

Originally Published -- 7:06 AM PDT