They are currently setting it up at the berry center in cypress. Since it's right near my house, I went out and checked it out a little while ago. Who's gonna go out and try to be a walk on?! Filming takes place this weekend sat/sun night. Ticket information is available here.
http://on-camera-audiences.com/shows/american_ninja_warrior
You can see the warp wall in the photo!
http://on-camera-audiences.com/shows/american_ninja_warrior
You can see the warp wall in the photo!