Other mistake: After Kirsten is talking to Sandy about the fact Seth got into a fight and she comes inside to see that Ryan has made breakfast, there is no way he could of set the table, found all the utensils and ingredients and cooked them by the time Kirsten gets back inside.
Other mistake: Near the end of the movie, we can see that the walls of Troy have suffered heavy damage from siege equipment, probably catapults. Yet in the entire film, we don't see any siege engines. The Greeks haven't brought any on their ships, we don't see them make any in their beach camp and they don't have any with them when they try to storm the city. There's simply no indication that the Greeks have ever had or used siege equipment.