In some scenes, watches are visible on the wrists of Roman and Dacian soldiers.
The movie mentions the "week" as a measure of time, but that was not part of the culture, and even the Romans had only a 8-day week for hundreds of years after the time of the movie.
All of the mounted troops use very obviously modern equipment. Most notable were the stirrups. Stirrups did not come into common use in Europe until at least the 8th century, long after the end of the Roman Empire.
In the 27th minute there is a brief (reversed) shot of the Roman soldiers running, with their ladders, away from the city walls rather than attacking them.