In the How I Met Your Mother episode “Game Night” (2006), Barney tells a story that takes place 8 years earlier. Which would be 1998. In that story, we see on a shelf in a coffeeshop a copy of Shadow Puppets by Orson Scott Card. Which wasn’t published until 2002.
All of HIMYM is now ruined for me. Nothing is believable.
Also I am hung over and can’t leave the couch.
HIMYM has established many times over that what you see on the screen with your eyeballs is a reconstruction of the scene as remembered by the storyteller. And in episodes like “Game Night”, it’s a storyteller recalling the storytelling of another storyteller. The narrator is unreliable.
Case in point: sandwiches.
On the other hand, this.