When a black hole reveals a clue left by an ancient race, the Callistos discover a secret galaxy containing the key to saving their own.
- Cullen McCarthy as Miles Callisto
- Fiona Bishop as Loretta Callisto
- Olivia Munn as Phoebe Callisto
- Tom Kenny as Leo Callisto/Alien Crowd/Dethalian Reporter
- Dee Bradley Baker as M.E.R.C./Alien Crowd/Alarbus Robot
- Bill Nye as Professor Rubicon
- Diedrich Bader as Admiral Crick/Trident Bot
- Danny Jacob as Admiral Waston
- Grey DeLisle as Stella/Alien Crowd/Oumou
- By the end of the episode, the Stellosphere, M.E.R.C. and the Callisto's spacesuits receive upgrades with the use of the new Galactech Globe from the Builders, as well as information about new galaxies to explore.
- This episode continues where "The Hitchhiker's Ride Through the Galaxy" left off, after Loretta and Miles unlocked the puzzle and received the message from the Builders.
- The Builders are introduced for the first time in this episode.
- This is the first half hour-length episode in the series.