The Aggravated Assault of the Alien Armada

The Aggravated Assault of the Alien Armada is the 6th episode of The Epic Tales of Captain Underpants in Space! and the Season 4 finale.

Synopsis
George and Harold discover that the Biglyans are using Melvin to enslave humans, so they escape in the Littleite ship. It turns out the ship is remote-controlled because Shifty Fitzgibbons is actually a Littleite named Itsius Bitsian, who was hiding his idenity from the Biglyans to protect his ship. Unfortunately, he failed and is unable to help them. No one would help George and Harold stop the Biglyans (not even Moxie Swaggerman), so George and Harold have no choice but to battle the Biglyans alone.

Trivia

 * This is the second episode where Captain Underpants calls Harold and George by their real names; he first did this in The Flustering Mindless Woe of the Flushable Memory Wipes.
 * There was a scene where Captain Underpants cries tears of joy. However, he didn’t turn back into Mr. Krupp. It could be possible that those tears were not strong enough to turn Captain Underpants back into Krupp. But in The Vexing Villainy of the Vile Vimpire, a single tear from Melvin was enough to turn Captain Underpants back into Krupp.
 * Captain Underpants turns back into Mr. Krupp at the end, but when Harold and George time travel back home, Captain Underpants returns when a second time machine shows up.