I found that jumping toward the fence causes the character to be "stuck" sliding on the collision. You can't jump again in this state (so no double-jumping over the fence), but as long as you keep holding the control toward the fence you won't fall to the ground, and you can kinda shimmy side to side. So you can end the game by going to the left edge of the fence, jumping to the right and hooking downward to stick to the back side, then shimmying over to the pavement. Kinda janky… Maybe the appropriate rule would be "Don't touch the back side of the fence"?