The boat in the opening sequence when Beef is singing "Way up here, you can breathe the air" changes its name and color in every episode. It's in the background in season one, but in the foreground in season two.
At the end of the opening to every show in season one, the family is sitting around the living room doing quiet activities. In season two, they're playing a board game.
In the intro when Ham sings "Or gaze at a Bear" there is a Yeti walking in the background.
All episode names end with the word Adventure.