As someone who's doing Latin at university, this scene never fails to make me laugh. However, technically ... ‘domum’ is ACCUSATIVE SINGULAR. Do all the Romans live in the same house? If you want all the Romans to go back to their individual homes, what you would have to say is ‘Romani ite domos’.
Additionally, the locative would actually be ‘domi’ (‘domus’, by the way, is one of the two or so words that still have a dedicated locative, the only other one I know being ‘rus’). However, the locative is used for position, not for movement; ‘domi’ means ‘in the house’. For motion towards, the accusative is used, which is indeed ‘domum’, meaning ‘to the house’ (or, as it should be, ‘domos’, since its multiple houses that we're talking about). Nota bene: It is indeed ‘domos’, and not ‘domus’. Even though ‘domus, -us’ is a u-stem noun, its declension is somewhat whacky: the ablative singular and accusative plural end in ‘-o’ and ‘-os’ (always) and the genitive plural in ‘-orum’ (often).
tl;dr: ‘domum’ is not the locative, it's the accusative; using the accusative here is correct though, except it should be plural: ‘domos’.