The Robinsons Were Here - S1-E4
Revealing mistake: After going beyond the perimeter fence for the first time, the children initially find the flowers that bloom when they each clap. When the robot motions to clap, you can see its left hand lost to the CGI flowers.
Answer: It's unknown how the eels got into all the fuel tanks. Once they were discovered, the colonists could flush them out of the tanks and keep them out before adding the fuel from the Jupiter that crashed in the desert.
raywest ★