30. The Timing
Whilst the first real jaw-drop of the show was largely telegraphed ahead of time, if you'd missed it in the build up then it'll have hit you like a ton of bricks in the opening. Starting Season 3 with a brief reminder of where we left things in Season 2, we're greeted with Laura Palmer literally saying the words "I'll see you again in 25 years".
We're closing in on closer to 27 now, but at the time the return of the show was announced, she was almost bang on.