Continuity mistake: Lily and Marshall mention that they've been using the same toothbrush ever since they've been together, but in the 14th episode of the 1st season, "Zip, zip, zip", Marshall and Lily are simultaneously brushing their teeth with a tooth brush each (before Ted and Victoria get home).
Trivia: When Ted and Robin are at the restaurant, they are accidentally sent a champagne glass with an engagement ring in. A man then claims the ring and proposes to his girlfriend. This couple really did get engaged on the show - the guy set up the surprise proposal, as his girlfriend thought they were just there as extras.
Marshall: You should definitely go. Look, it's a chance to show her you are still friends and that you support her.
Barney: Or it's a chance to mess with her head by showing up with someone hotter, or even better, triple threat, hotter and bigger boobs!
Ted: That's only two.
Barney: Count again.