When Ted is narrating the story to the kids that he and Stella would have had if they had gotten married, the little yellow bus that belongs to the actual mother is present on the ledge behind the couch.
When you see Barney working in his office there is a "Perfection" poster hanging on the wall behind him next to the "Teamwork" poster. One scene later you see the "Awesomeness" poster at this spot.
Stella states that she is born and bred in New Jersey, but in the scene where she talks about Tony not letting her daughter go to the wedding she speaks with a clear Canadian accent - her pronunciation of "aboot" as Robin is generally teased for is a dead giveaway.