Adam just brought that one up in one of his public Q&A's on youtube in the past week or two. They hid the mouse under break away poo and when the poo opened they got spooked, so they tried it another way where nothing looked like it moved and they still responded but it was more not to squish it.

Yeah it was something along those lines.

They were speechless when the first elephant turned away, which is a pretty strange reaction for that crew. Makes me chuckle just thinking about it. They were completely floored, you can almost hear what they were thinking: "This is a dumb myth and why are we wasting our time.... .... .... what just happened?"

Hyneman's take was that the elephant appeared downright scared of the mouse.

https://youtu.be/GTuS1ISYEak