When Shovel says that he used to be scared of Dinosaurs, he is referring to Prehistoric Blue, when he heard dinosaur like noises in the garden, thinking there was an actual dinosaur and it's prey was Shovel.
The character Felix in this episode first appeared in The Lost Episode! and the "Go Back" song is also from that episode.
Also, Felix is apparently voiced in this episode by somebody other than who voiced him in The Lost Episode.
This is Felix's third appearance in the show.
This is the 2nd episode where Blue leaves a clue onscreen.
This is also one of the few episodes (if not the only one) where Blue puts a pawprint on the screen twice in the same episode.
In the Mailtime segment, there was only 1 human kid introduced in the letter.
The closed captions read "Boy" when Felix was first heard calling to Joe.
The part where Blue and the viewer sing the "Go Back" song, this was a reference to The Lost Episode!.
This is the second episode where the clue is a door. the first being Adventures in Art.
This is the first episode with Joe to air on Noggin.