so i was playing x-men on snes and this happened.. was this a gaming glitch? 

 https://youtu.be/on6tmtt9ab0

The game was going to punish you for missing all those power ups but at the end it became conflicted because it thought you were
kneeling in homage of its splendour, and ended up in a logic loop.

Just guessing here but it looks like the condition in the code for the mission complete screen to initiate is for the boss's HP to hit zero and that it doesn't consider the state of your character's HP. The developers probably didn't deeply consider the case where concurrent hits occur and both characters get KO'd (I am guessing that it doesn't happen very often). That said, at the very least, there should be a condition in the code that prevents your character's death animation from initiating in this case.

It's not really what I would call a glitch though, more just an oversight. Gamers will generally be happy since they still get the win. I wouldn't be surprised if it got identified during testing, but it just wasn't enough of a problem to justify a code revision (assuming that it is very rare). That said, if this were a game made by a perfectionist developer like Nintendo EAD, you can bet that it wouldn't have been there.