Oh god, MISSINGNO
For the more simple minded of you out there, MISSINGNO was a glitched Pokemon that could fuck up your game badly if you weren't careful. Also, MISSINGNO simply means "missing number", the game had no data for it.
What's funny is that I indeed did get one of these, and I believe I got all the way to the Elite 4 with it. Funny thing was, one day I started it up, and it said my save data was corrupt. It was a sad day indeed (mind you, this was when I was like, 8).
At first the movie is based around MISSINGNO, but gets more random as it goes on. From him pushing out the cartridge to jumping into the FF7 world, and having MISSINGNO corrupt that save (we all know how blasphemic it is to have corrupt FF data, especially late game)
Still loved Barret in there too:
"What about me?"
"Oh you were, um... uh.... there..."
"I SAVED YOUR SKINNY WHITE ASS!".
Good stuff.