The New M.A.V.O. Member - S1-E10
Question: When Teddy and his friends shrink down to get the crystals back they know that five crystals are real and one is a fake salt crystal. How did they know which ones were real and which one was fake?
Answer: Grubby licked them and could taste the salt.
Answer: The only guess would be that the real crystals and the fake salt crystal look different somehow. They made the fake salt crystal, so they should know what it looks like compared to a real crystal. Also, they could have very easily done something to the fake crystal that was stolen from them so that they could tell it apart from the others.
Question: Is MACC inspired or copied from Johnny 5 from Short Circuit?
Answer: Although the series creators have never confirmed this, it seems fairly obvious that MACC is inspired by Johnny 5.
Answer: Yes but MAVO had five real crystals and one fake one, and they all looked the same. There was no way of knowing which ones were real and which one was fake.