Apostrophes don't work. Throws a JS error in browser console
Observe.
[spoiler=This spoiler works perfectly!]I'm going to put an actual spoiler for Assassin's creedin the other spoiler, because it doesn't work and you won't see it anyway.[/spoiler]
[spoiler=Click me! I don't because I have an apostrophe!]Desmond dies at the end of AC3.[/spoiler]
Edit: Forgot to mention that spoilers still have the data behind them, ie. visible when quoting.