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.
Revealing mistake: When the assistant gets thrown into the wall by the brain controlled Gar-tiger, there are already marks on the point of impact, from previous takes.