In the final episode, in which the Curious Orange becomes the citric equivalent of Davros from Doctor Who (1963), Curious Orange was originally to have been defeated by Tom Baker. Baker declined, saying that the part was "not for him".
The Curious Orange is pulped to the tune of "Orange Crush" by REM.
In the second series, the Curious Orange was temporarily replaced by the Curious Alien because Paul Putner (who played the Orange) was filming for Dark Ages (1999) at the time.
On one occasion, Stewart Lee sings the "Trevor and Natalie" song to the tune of Radiohead's "Everything in its right place".
Stewart Lee tells the Curious Alien that even though it is alone in the Universe, he loves it more than life itself. This is similar to the typical "Adoption Speech" some children receive, and Stewart Lee was Adopted.