While Gladiator is a cinematic masterpiece, to which a tremendous debt is owed for the revival of interest in the classical world that it irrefutably inspired, there are of course notable historical inaccuracies. Many are trivial, and even simply visual.
One egregious example, however, that diverges significantly from credible reality, is the script having Emperor Marcus Aurelius declare his wish, in what then serves as the driver for the entire plot, for Rome to "be a Republic again".
This dialogue, along with another prior line, when a senator utters "Rome was founded as a Republic", despite the Eternal City being birthed under a monarchy, was almost certainly inserted as, at best, a fiction for narrative purposes, or at worst, a Trojan Horse to implant political beliefs dominant at the turn of the 21st century into a character of the classical world widely revered as virtuous.
"Had father had his way, the empire would have been torn apart", Commodus remarks, several scenes later. Unfortunately for the writers, the man presented as the antagonist of Gladiator appears to have a better grasp of politics than Marcus Aurelius, and perversely, virtuous government too.
Except for in the symposia of a handful of idealistic patricians, by the 2nd century AD the Republic was overwhelmingly seen as a disastrous failure, under which the provinces had been ruled as kleptocratic fiefdoms of the oligarchic classes, presided over by a Senate in Rome that was at once devoid of any meaningful authority, since private interests controlled the Roman state so completely that holding public office was entirely meaningless by the days of Julius Caesar.Richard Harris as Marcus Aurelius
Indeed by its final decades, the status quo was entirely untenable, with the Republic locked into a perpetual cycle of civil war or the imminent threat of it, while unrest in the provinces was a regular occurrence. It is often forgotten that all three of the great slave revolts in Ancient Rome occurred under the Republic, not the Empire, with Sicily being a particular hotbed of unrest, on account of the island being dominated by absentee Roman landlords who flooded it with slaves transferred from Asia, and who leveraged their political connections in Rome to avoid prosecution - Gaius Verres being the exception that proved the rule.
Worse, tax collection under the Republic was outsourced to private entities, who readily and frequently extorted the provinces where they operated, free from the authority and oversight of the Roman state. As the historian Michael Crawford adroitly observed, a Roman magistrate hoped to make "three fortunes out of his province - one to pay his debts, one to bribe the jury if he were brought to trial, and one to keep himself."
Under the Empire, notably under Augustus and especially Domitian, taxation was brought under much tighter supervision, eliminating one of the gravest injustices of the Roman state.Marble bust of Marcus Aurelius Antoninus
(b.121-d.180), Musée Saint-Raymond
That any Roman Emperor, and the philosopher Marcus Aurelius above all, would have sought the restoration of such a system is divorced from reality, and flies in the face of the overwhelming evidence that the Empire, at least in its early centuries, represented an objective improvement in the quality of governance for its citizens and subject peoples.
What makes the depiction in Gladiator even worse is that the film clearly establishes both through other characters and the dialogue of Marcus himself that the Senate is corrupt beyond all hope. Yet his bright idea on his deathbed is to surrender total power to them, apparently trusting a lone Maximus with few allies will not be immediately assassinated upon trying to "end the corruption that has crippled it".
The Republic not only failed to restrain the excesses of the oligarchic classes, it both actively and passively enabled them, and the notion of its return would have horrified the true Emperor Marcus Aurelius.