OMG I FOUND THE FUNNIEST GLITCH!
Try putting 2 enemy catapult on the same place! And see how SCIENCE WORK!!!
The catapult will start flying! Well if it doesn't works when you tried it, I'm sorry I wasted your time :(
It's a planned feature :P
I will look into it, thank you for reporting!
I was making my execution castle thingy and I accidently double click and I was like... Why are you flying to the abyss without my permission... And I was laughing so hard!