The Belchies - S2-E1
Continuity mistake: After they escape the tunnels, Tina's shirt instantly brightens in colour after she comes to a standstill.
Burgerboss - S2-E4
Other mistake: Throughout the episode, the buttons on the video game change or disappear in some shots. For example, when Bob first asks for Darryl's help, you can see there's no buttons on the game.
Burgerboss - S2-E4
Other mistake: When we first see the high scores for the video game, JMC has 99,550 points. But later only has 99,520 points.
Continuity mistake: The pillow disappears and reappears between shots while Gene is on the bed. Interestingly, the wrinkles his feet make in the pillow can still be seen floating in midair in the shot where the pillow itself is missing.
Answer: It's a made up song for the show. It's a synth version of what the kids sang in Mr. Frond's video at the beginning of the episode. "Let's Swap Eyes."
Bishop73