I just attached a minion to my pet but I wonder now if that's a mistake. Can the rays zap minions while attached?

Yes, the V2 pet zapper can randomly zap your active pet's attached minion into a type of Slime (Prismatic, Clear, Glowing, or Opaque)

Eesh, better remove. That minion is worth too much. Thanks!

I would recommend buying a cheap minion to attach to your zapping pet just in case the minion does get zapped--the slime are possible stat booster items so they are around like 100k-200k in price.

Oh, that is really good to know! :D Thanks.