Leonardo is first shown watching Space Heroes in Rise of the Turtles, Part 1. He memorizes one of Captain Ryan's speeches and quotes it verbatim later in the episode. He also imitates Ryan by slapping Michelangelo in an attempt to calm him down.
Leo watches the show again in I Think His Name is Baxter Stockman, Metalhead, Panic in the Sewers, Mousers Attack! and It Came From The Depths. Each time, Space Heroes seems to foreshadow something that will happen later in the episode. For example, in Metalhead, an alien takes control of Dr. Mindstrong by attaching itself to his head. The same thing happens later when a Kraang takes control of Donnie's robot, Metalhead.
There is also a Space Heroes pinball machine in the lair, which Raphael can be seen playing in the opening. Donatello uses the back of a Space Heroes movie poster for his "Hang with April" flowchart in Monkey Brains. The poster is a reference to Star Trek III: The Search for Spock ("Space Heroes III: The Resurrection of Mindstrong"). Leonardo also owns a vintage Space Heroes comic book, which is modeled after the first Star Trek comic from 1967.
In Season 1 of the series Leonardo watches 10 episodes of the show.
- Captain Ryan - the leader and main protagonist
- Crankshaw - a young ensign who Ryan slaps every time he starts panicking
- Dr. Mindstrong - an alien scientist
- Commander Grundch - the second in command
- Rodriguez - crew member in orange shirt from Mousers Attack!
- That Other Guy - crew member in purple shirt from Mousers Attack!
- Celestial - Captain Ryan's love interest and enemy
- Hypnotica - evil alien who controls Captain Ryan
- Panicons - evil giant robots that shot Captain Ryan with their Anxiety Ray in Panic in the Sewers.
- Trumplets - cute inconvenient furry creatures (an homage to Star Trek's Tribbles, but with organic trumpets added)
- Cortexicons - a creature that took over Dr. Mindstrong's mind in Metalhead
Episodes featuring "Space Heroes"
- Rise of the Turtles, Part 1
- I Think His Name is Baxter Stockman
- Panic in the Sewers
- Mousers Attack!
- It Came From The Depths
- New Girl in Town
- Karai's Vendetta