One of the cool aspects of PEPLUM films is seeing films with scenes set in the arena with elaborate set-ups. Here are just a few examples. These don't include scenes with standard gladiatorial arenas but just those with added themes or contraptions.
A mock fortress surrounded by a motte in FABIOLA
In SPARTACO : SINS OF ROME, a full ship with oars in a pool of water
An elaborate elevated fighting area in BARABBAS
GLADIATORS 7 : An elevated catwalk area to fight, with wooden spikes waiting below