The costuming in Gladiator is exquisite, but the "battle" tactics are absolute carp

Roman archers and artillery formed up behind the legions historically in open battle (according to what few references we have), and the flaming arrows, etc were nonsense.

The initial charge of the barbarians would have been taken by Auxiliaries not legionaries, and it would have ben a foolhardy General taking himself out of the fight for 10 minutes to charge around behind the enemy on horseback - certainly he would have had troops hit them in the rear, but he wouldn't have gone with them.

But the costumes and the dirty sweat stained unshaven bandana-ed grumbling legionaries were just lovely