So we did a naughty thing and broke into a base. We broke through a gate that had barbed wire mounted in the bottom position. We didn't have pliers, so we just broke down the lower/upper walls and frames and jumped over the barbed wire, which was still across the gate opening.

Later someone came by with pliers and dismounted the barbed wire. Suddenly the gate was visible again with only the lower wall part missing. There was no collision - you could walk right through it - there was only a visual representation of the gate.