Sorry if this is redundant : game.fade_and_teleport(0,0,0,5119,460,550) will teleport you to a colosseum. Look into MapNames.mes and check the maps without name. Most of them are in the game ( like the opening vignettes), but not all.
Sorry, the last two argument should be 487 and 506. game.fade_and_teleport(0,0,0,5119,487,506) This will teleport you inside the arena.
Ha! Someone apparently did discover this before me. Why didn't this post show up when I searched for "Colosseum"? Does the search option not work for older posts?