There's a few that come to mind:
1990 Phoenix Grand Prix
A Minardi qualified second, a Dallara third and a Tyrrell fourth on the grid!
1991 Phoenix Grand Prix
Mika Hakkinen spins in a straight - the cause? He had managed to pull the steering wheel off.... What's even more "What the?!?" is that he re-attached the steering wheel, and continued the race... then retired later on in the race!
1991 Portuguese Grand Prix
Nigel Mansell is overtaken by his right rear wheel as he speeds off down the pitlane
1991/1992/1993 British Grand Prix
Ayrton Senna retires from the British Grand prix 3 years on the trot, at more or less the same corner each time...
https://www.youtube.com/watch?NR=1&v=iZvx3gFHV7o&feature=endscreen - and in both 1991 and 1993 he ran out of petrol!