okay, what the hell, I crossed the finish line with a "2" on the upper left corner. So I was expecting a number 2 neon light on my screen but instead it showed a 3. Then, the top 3 would be showed right? Guess what, I wasn't part of them, apparantly I was 4th. Is this some kind bug?

" ...Is this some kind bug? "

This bug seems to occur when someone's lagging, from my experience. Once the game catches them up, it'll put them past other players if they finished with a faster time.
 
Kind of cheap, especially since the lag typically means you can't hit them with weapons, but I've only experienced it once or twice.

people register as ahead of you when they are invisible, right? Of they dont then that perk is pretty badass.

" people register as ahead of you when they are invisible, right? Of they dont then that perk is pretty badass. "

If you consider that a 60 FPS one frame is 1.7 hundredths of a second.  Toss in a little bit of lag and it's pretty reasonable that sometimes you'll get "cheated" out of a razor's-edge finish.  It sucks, but there's only so precise an internet game can be.