When Joe asks the Giraffe if it gets a ball off of roofs in its natural habitats, closed-captioning reads "rooves," but the proper spelling is "roofs."
In the Mailtime Segment, Joe tries to sing the Mailtime Song, but is interrupted by various animal noises. Afterwards, Mailbox has him receive his letter from a goose that's been hanging around the house.
The goose also gave Joe the notebook by Sidetable Drawer.
When Joe is looking for the 3rd clue (on the pocket located in the middle of the overalls), Joe goes behind the other outfits in the clothesline, posing as if he was wearing them.
Also when the animals show Joe and the residents of the Blue's Clues house what they do, Joe gives out a quote like: "Great swimming, Platypus!", "Terrific tusks!", That's a beautiful house, I mean lodge, Beaver." and "Enjoy your snack, Giraffe." just to name a few.
The game board seen in the bedroom is the same one from Geography.