Hollywood only knows one thing about Roman tactics, and that's TESTUDO

Explanation: The testudo formation was a distinctively Roman and very useful formation - but not in close combat. It was very much a niche tactic for a Roman unit to defend itself when under heavy missile fire - it is explicitly noted by contemporary writers to have been unsuited for a melee. Hollywood never got the memo.

hbo's Rome did it right. they show it one time and it's in response to arrow fire.

otherwise they have legates organizing spear lines and using whistles to time and position them. it was actually quite well done.

Watch as Gaulic/Celtic tribesmen leap over the shields