For the "escape proof box" skit, the box was completely ungimmicked. Rena really did kick her way through the side to escape.
Rena performed the "vertical buzz saw" illusion for real; she was offered a stunt double to take her place, but this would have prevented the audience seeing her get inside and be chained in place.
The brief silver bikini Rena wore for the buzz saw illusion was not just for show - it avoiding clothing that might get caught during the performance.