An evil space pirate named Gloomius Maximus (Voiced by James Woods) tries to drain all the happiness and fun out of everyone. Unfortunately for Olie, an invitation to Zowie's third birthday party accidentally flies off into space and makes its way aboard Gloomius's ship. Gloomius never had a birthday party himself, so he sets out to make Zowie's as miserable as possible. He zaps the robots with the Glum Beam and takes them to the Galaxy of Gloom. Between Olie's super silly ray and some help from Saturday morning heroes Space Boy and Space Dog, the day is saved by silliness. In the end, Gloomius Maximus becomes good.
- This is the last time Joshua Tucci voices Billy. Tucci was replaced by Kristopher Clarke in the sixth season and The Baby Bot Chase (also known as The Great Baby Bot Chase)
- This is the only film that Young Percy and Gizmo appeared in.
- This is the only movie where Precious the cow is absent.
- This is the Jollie's first appearance on the show.
- This is the first movie that involves Zowie's party.
- This is the last time Rolie Polie Birthday was performed since Spot's Birthday in 1998.
- This is Wheelie's first film appearance until The Baby Bot Chase.
- This is the only episode that Gloominus is voiced by James Woods. Woods was replaced by Paul Haddad starting in Give It Back Gloomius
- This is the only episode where CooKoo doesn't appear.
- This is also the fist appearance of Gloominus Maximus's henchman The Baddies. They appear again in Give It Back Gloomius,The Baby Bot Chase and Shhhhhh!!.
- This is the first and only time Space Boy's theme doesn't play.
- This is also the first film to have re-composed music.
- This is also the only time that the theme song is sped up and the first time the theme was performed with different singers. The second is The Baby Bot Chase.
- These are Galaxy of Goofs' first film appearance.
- This film is Willie and Wollie Jollie's first appearance on the whole show. They appear again in The Baby Bot Chase.
- On the DVD version of this film Olie is the guide of the film's main menu.
- This film takes place between the fifth and sixth seasons.
- This is also the only of 2 films where Clock Mouse is absent. She will return in the sixth season.
- This is the first and only film aie Pi appearance of Screwy.
- This is the only film where James Woods voices Gloomius Maximus and he was replaced by Paul Haddad in The Baby Bot Chase and Give It Back Gloomius.
- This is the first and only film to feature a bonus episode on both the video version and the DVD version.
- This is also the first film appearance of Doctor Callinghouse since he first appeared in the Ten Foot Olie episode.
- This is the last of 2 films that Len Carlson voiced more characters other than Pappy until his death.
- Paul Haddad joins the voice cast as one of the Jolly twins until Shhhhhh!! where they made a short cameo with no speaking parts.