The biggest plot hole of Gladiator

The biggest plot hole is in the beginning of the movie.

Roman army just won a critical victory against Germania tribes. Most of the camp are occupied by legionnaires under the command of Maximus, with only a tiny number of Praetorian Guards spread among them.

Secondly, as the commander of the largest and most crack army of the whole Rome Empire, it is unimaginable to assume Maximus is not under the close protection of his own guard units. Remember that even after the big head-on victory, there are still occasional barbarian raids here and there.

In any case, I don't think the crowned prince (not having the throne at his hand just yet) has such capability and authority to order the murder of the commander of a victorious crack army in its own camp, right within the general's own tent (which should definitely have been under the heavy protection of the general own security units).

That's totally unbelievable, even with the help of Quintus (clearly, he doesn't enjoy the same level of love from the soldiers and doesn't command the same level of loyalty from them, as Maximus does).

The black armor of the Praetorian Guards is hinting that they are something like SS in the Third Reich. However, in the real history, Praetorian is a force to be reckoned with, only inside the wall of Rome city.