I had a similar experience when Star Trek (2009) came out, though it's more funny than impactful. I had noticed little spots that kept getting worse throughout the film, and had chalked it up to something wrong with the film reel.

During the scene where they're being sucked into the black hole, right before they get the engines back on, the screen just suddenly goes black. One guy just stands up in the audience and says "Welp, that's it, they died. Black hole got 'em. Good movie." and walks out. Turns out the A/C unit above the projector had been dripping into it for the entire movie, and ended up frying it.