About Jax choosing red button
I think some people are taking Jax's words in that scene too literally.
"You dirty liar! You scumbag! You– You made me– You got in my head. You just lie about everything don't you?"
It's not Cain controlling or influencing Jax to push the red button, nor is it Jax placing blame onto Cain to save his skin.
What really happened is Jax was fully convinced it was just another adventure... until he wasn't. And the moment he starts thinking that this might be the real thing, that they may actually be able to leave the circus, it terrifies him to the point of panic attack.
You can notice that it starts in the hall, before they even enter the computer room.
Cain's "world-building" got to him. By creating this storyline and making it believable enough Cain "made" Jax press the red button – right in front of everyone.
He made him reveal that he'd rather stay in the circus then go back to real world.
That in his panic he would have trapped everyone else with him.
And he revealed it for nothing.
"You can mess with our minds, too, can't you?"
This line comes up not because Jax thinks/pretends Cain mindcontrolled him into pressing button but because it's another thing Cain openly lied about. (You can see Jax making connection after "you got in my head" sentence. It's a chain of thoughts.)
And Jax (like the rest of the group) is sick of being toyed with.
So while I believe Cain is capable of messing with mind, nothing really suggests he used it in this adventure.
Anyway, I can't wait for the next episode, what an amaizing series