Corrected entry: At the start of the first battle when we see Maximus riding on a horse, he comes across a Germanian about to stab a soldier. He rides along and cuts the guy's hand off. If you slow this part down, it's not blood that comes out the wound but what looks like bits of wood. (00:09:55)
Corrected entry: In the scene where the two senators are quarreling about the note about the gladiators, we can read: "gladiatores violentia." This is an encroachment on Latin grammar. Since gladiator is a male word, a corresponding adjective should be male too. Also, violentia is a noun. The correct form would be 'gladiatores violenti = violent gladiators' or 'gladiatores violentae = gladiators who fight like girls' depending on which school of thought you ascribe to (the latter being the claim that it is an informal use of Latin, insulting the gladiators by slighting their masculinity, accusing them of an effeminate form of fighting.).
Corrected entry: After the battle against the Germans, Maximus lets out a cry of victory: "Roma victor." This is supposed to be Latin, but, they got the grammar all wrong. "Roma" is feminine, so it should be "Roma victrix". Amazing how a mistake is still possible as there are only about three sentences in Latin in the entire movie and a lot of specialists were supposed to have been working on it.
Corrected entry: In the real gladiatorial games of ancient Rome, the emperor didn't make the gesture of "thumbs up" (kill) or "thumbs down" (live) That was the job of a referee, even though it isn't as dramatic. Also, the thumbs down sign usually didn't mean death for the defeated gladiator, but instead he would face a flogging.
Corrected entry: The Emperor tells Maximus that his son "squealed like a girl when they nailed him to the cross". But we've seen that he was trampled by the horses, so: what did they crucify him for and how could he have squealed? The Emperor could be just lying, but anyway he says "nailed him to the cross" and there was no such a cross (what we see looks like they were hung).
Corrected entry: The forest in the opening battle scenes is man-made and not the natural, wild forest that would have covered Germania at this time. The trees are all in nice straight lines, there are no low hanging branches and no tangled growth on the forest floor. If this were a natural forest the Roman cavalry would not be able to gallop through it and weave effortlessly between the trees as is depicted.
Corrected entry: In the first battle against the Germanians, after the Roman army shoots their arrows, if you look hard enough, you'll notice all the soldiers aren't "real" people. Some of them are obviously mannequins and they just stand there.
Corrected entry: When Maximus is in the arena with the tigers, the tigers have chains around their necks, and several men on the end of the chains to control how close the tigers get to the gladiators. But why don't the tigers just turn around and attack the men holding the chains? It seems unlikely that they'd know which humans to attack and which ones to leave alone.
Corrected entry: In the first battle scene against the Germanians, right after Maximus gets dismounted, he is lying on his back and an enemy soldier takes a swing at him with an axe. Maximus blocks it by holding the sword handle with his right hand and putting his left hand on the top of his sword blade. With the amount of force the axe came down with, blocking like that would surely cut off one's own hand.