Other mistake: When the girls steal a cab, there are some bystanders on the curb opposite to them. A woman next to a guy with a hat points at the camera for several seconds (for it's not a plot-wise movement).
Other mistake: The cofferdam outside the vault is no more than a few metres tall; the sea level seems barely high enough to cover the vault's entrance. However, once the dam is breached, the rushing water doesn't stop at the ground floor but covers most of the facility, rising much higher than would be reasonable.
Other mistake: In the first scene, they skid around a corner; there are many other skid marks on the same corner. I imagine the drivers had to repeat the recording several times.
Other mistake: When Commander Krom meets with Larry at the bar, there is a visible can of Axe body spray on the counter between them.
Other mistake: Macrinus and one of his high-ranking friends are discussing Lucilla's son, who disappeared when Commodus died. The guy says that Lucius disappeared when he was "about 12," but in the original Gladiator, he was barely about to turn 8. They also say these events happened 16 years prior, but, again according to the movie lore (without even looking at history), he died in 180 AD, and this movie is set in 200 AD.