In the UK, Kevin still wears his green striped shirt before switching to the green square shirt in the UK version of Shape Searchers. Kevin also uses the notebook (used by Joe) for the first time, given to him by by Sidetable Drawer.
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 second 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.
Although this is the third time it's happened in the series, it's the second time Joe's hair changed throughout the entire episode. In Joe Gets a Clue, his hair did not change until he was receiving his notebook from Blue. Steve Goes to College was the first episode in which Joe's hair changed throughout the entire episode.
This is the first episode with Joe to air on Noggin.