Series you can watch a million times and always find something new
So, I'm a pretty diehard FMA fan (especially the first anime), and I've watched it a bunch. That said I recent started watching One Piece. I get to the first few episodes with Usopp, and I'm reminding of a line from Maes Hughes, to roughly paraphrase: "What do you want me to do? Take out my slingshot." Now, this is especially funny when you consider who voices these characters in the English dub. I'm not sure if it was an intentional actor allusions of Funimation's part, but once I made this discovery I like LOL'd for a minute.
This is just one of the ways you know you're doing your job as a storyteller when your audience still finds something new even after they've experienced your story several times. I must have watched the entire original FMA anime a dozen times and only now picked up on that. And there are a lot of stories out there that can do this. I'm still finding new things when I pick up my copy of Watchmen.
So, does anyone else have any similar experience with media? Films, shows, comics, songs, whatever?