It doesn't happen very often these days, but there was a huge spoiler just hanging out online for anyone to see, and somehow no one noticed it.
The Flash's Teddy Sears (Jay Garrick, Zoom) was featured on Kevin Smith and Marc Bernardin's Fat Man on Batman podcast and was asked how close he's been to slipping up and telling people about his part. It turns out very close, but it wasn't his fault.
"So I signed the contracts, and great, I'm gonna go do this for the season. It shows up on IMDB, like, I don't know, I'm talking like a day or two later, and I'm on IMDB because I'm going to add a Masters of Sex credit. This is June, so I go on to add a credit and I remember, it says Flash - Jay Garrick/Zoom, spoiling it right there. So I'm seeing this and I'm like this is, okay, this is weird, and it has all these episodes spelled out, but they don't have titles, so like 1.1, 1.2, whatever. I don't think much of it because I think well, you know, someone put that there so someone must know what they're doing."
It didn't take long though for someone to find out, but luckily it was the studio. Sears continued: "Like a day later, or maybe I don't know, later that day, Kreisberg sees this, I don't know how it came to his attention, but he sees it. He calls my agent, he calls my manager, convinced that they must have put that on IMDB because no one else knows this. They know it because they were privy to this conversation, so it must have been them, and neither one of them, they just don't do that."
As to how the information got on IMDB in the first place, most likely it was an inside leak. Sears concludes: "I think we figured out that it was probably someone in the office at Warner Bros. that saw the contract, and said oh, he's playing these two characters and just entered it in, I don't know how it happened. It was taken down really quickly, but there was, if someone had gone onto IMDB during that day or two, and luckily no one was looking, no one gave a s***, but could've easily been like 'hey!'. That was the closest, and like talk about whisker close actually."
I'm sure spoiler hunters everywhere will make sure that a big catch like that doesn't slip their grasp again.