The most obviously blown call that resulted in a big play in a big game?
1988, at UCLA. The Bruins ring up 28 points in Q1. Early in Q2, Mark Blazek picks off a pass and falls to his knee. It's not that his knee scraped the ground, he came down solidly. Then he gets up, looks around, and realizes he never heard a whistle, and starts running to the end zone. Players on both sides are coming on and off the field. Blazek goes 75 yards untouched and unchased. Never a whistle. The ref shrugs and signals touchdown. UCLA scored the next 10 and NU was never in the game, so it's pretty well forgotten.
1982 Penn State out of bounds catch was kind of bang-bang. It really wasn't close but you can see how an official could blink and miss it. But it was a huge blown call because of the timing. I consider it the most damaging because we we had a truly awesome team and never got a shot at the title.
94 FSU OB, bad calls, but both judgement calls. I don't recall the clip that well but the non-fumble was in a pileup and not too easy to see.
The Wiggins kick could've been called but that's really a judgement call on intent. He didn't kick at the ball, it landed on his foot. I believe he probably lifted his foot up to keep it alive, but could a ref really make that judgement? It definitely could've been from the hit.
I had always thought the Ruud hit on the kickoff in OU 1978 was a horrible call but I heard a couple years ago that the returner was called out of bounds when he caught the ball, before the hit.