These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Better on DVD: The DVD includes several deleted scenes that add to the story, such as a scene where we learn that Commodus is selling off Rome's grain stores to pay for the games, and another scene where Commodus has two innocent praetorians executed because Maximus is still alive (explaining why Quintus refused to give him a sword during the climactic battle).
Big Lipped Alligator Moment: The battle in Germania includes a sound clip of African war chants from the film Zulu as a Shout-Out. It can be jarring if you're familiar with the other film because of the anachronism and cultural difference.
Complete Monster: The power-hungry, violent, incestuous Emperor Commodus is the heir to the wise Emperor Marcus Aurelius, but when he learns that his father wants to make Rome a republic again and appoint the noble General Maximus as regent instead of him, he kills Aurelius, frames Maximus, and orders the death of Maximus (who escapes) as well as Maximus's wife and son (who don't). He casts himself as an unworthy son to a father with high demands, but his Patricide and subsequent megalomania show that his grievances with his father only reflect on his desire to become ultimate ruler, not to make his father proud. He becomes Emperor, and marginalizes the Senate's authority while keeping the populace in line with food and games. When Maximus reappears in Rome and the possibility of revolution looms he goes completely off the rails. He tries to have Maximus killed in the arena, but this fails. He then lures his enemy into a trap and unfolds the insurrection, killing most of Maximus's sympathizers and planning to execute the rest after publicly killing Maximus himself in a spectacular showdown, which he shifts in his favor by secretly wounding Maximus before the fight. His "love" for his sister Lucilla is later revealed to simply be lust, and when he learns that she is working with Maximus, the "merciful" Commodus demands that the horrified Lucilla provide him with an heir so his "blood pure" progeny can reign as tyrants for a thousand years to come. He threatens to kill his own nephew (Lucilla's son) if Lucilla doesn't consent to becoming his personal sex slave, or takes her life to defy him. Even the Praetorian Guard (his personal bodyguard, who are paid to protect him at all cost) are so disgusted by him by the end that they refuse to aid him when he loses his sword in the final fight.
Before the battle with the Germanic tribes at the beginning of the movie, Quintus' remark that "a people should know when they're conquered," is very ironic to anyone who knows that Rome never ultimately managed to completely conquer Germania.
When he first meets him in the arena (before realizing who he is), Commodus tells Maximus that his nephew "insists you are Hector reborn...or was it Hercules?" The real-life Commodus believed he was the reincarnation of Hercules.
Hilarious in Hindsight: Since Pirates of the Caribbean came out the epic soundtrack of Gladiator brings to mind the quirky antics of Jack Sparrow more than the epic deeds of Maximus. note Due to Hans Zimmer composing both scores, the films share many similar musical cues and motifs.
Jerkass Woobie: Commodus might be pitiable, for he had never got the love and acceptance from his family or people in general that all human beings want. Fortunately, the fact that he murders his own father and Maximus' family, repeatedly tries to kill Maximus himself, has incestuous feelings for his sister and ultimately blackmails said sister into being his own personal sex slave(using her son), makes him quite difficult to fully sympathize with.
Moral Event Horizon: Commodus crosses this either with the murder of his father, the Emperor, or with the the brutal murder, rape, crucifixion and other off-screen atrocities committed against Maximus' wife and small son, who is ridden down by horses. Commodus only goes downhill from there, first by threatening to kill his own nephew unless his sister becomes his sex slave, and finally by fatally stabbing Maximus before turning him loose in the arena.
Narm: This movie is so steeped in Black and White Morality that the story/plot can become this after a few views. On one hand we have Maximus as an impossibly perfect Purity Sue/God-Mode Sue protagonist who oozes Mangst, on the other we have Commodus as an impossibly incompetent and bratty Card-Carrying Villain. And then the script blatantly tries to manipulate the viewer's feelings towards Maximus via making him increasingly tragic and making Commodus even more evil if that's even possible. It's almost a bit insulting to our intelligence. On the other hand, the performances (particularly Russell Crowe's, Djimon Hounsou's, and Oliver Reed's) rise above and even elevate the material at several points, and it can't be denied that many viewers were deeply moved by Maximus's plight and story arc and found Commodus's death quite cathartic. Strictly Formula, but Tropes Are Not Bad.
Narm Charm: The first fight in the Colosseum - the reenactment of the Battle of Carthage - is intercut with shots of Commodus giggling and making silly faces. It's kind of hilarious.
Commodus yelling "AM I NOT MERCIFUL?!" is very over-the-top, but that doesn't make it any less terrifying.
Translation Convention: English for Latin, as it's expected for main characters. Yet in the battle scene with the Germanic barbarians, their leader howls in German something of cutting the Romans into dog food ("Hunde Futter"). Little is known of the Primitive Germanic language of 2nd century CE, but it definitely wouldn't sound like Modern German.