Talus' army uses counterpoise trebuchets. The big sling shot weapons with the counter weight. This particular type was not invented until the middle ages around the 11th century. If we follow the time line of the other movies that places them about 3000 years before they were invented.
Talus and Mathayus both use telescopes. Mathayus uses a crystal that he moves to focus. Talus has a glass lens telescope which was not invented until around 1608. This is about 2500 years before the movie is supposed to take place.
When Talus is cornered by Cobra's army outside the city walls, he looks back to see Mathayus coming through the smoke after the explosion. Mathayus has soot smudges on his face and arms. The shot goes back to Talus and again to Mathayus. This time, Mathayus is clean.
During the fight between Silda and Tsukai, Silda starts the fight using two swords but changes to a single sword mid-fight, then back to using two swords. Throughout the sequence,Silda does not appear to drop or pick up the sword, nor is there enough time to perform that action.