Lycus disguised himself as a woman in a yellow gown, but the gown changes to white during the chase scene and remains white for the remainder of the film.
Marcus Lycus, while disguised as a woman, reaches for a coin. In doing so, he takes the veil off his face. When he hands the coin to a guard, the veil is instantly covering his face again, even though he is not shown moving the veil.
In Lycus' house after Captain Miles Gloriosus and his soldiers arrive, one of the soldiers gets up and chases a girl. On the way he passes a juggler who use apples for balls and the soldier tries to catch one of the apples in mid-air. He fails to catch it but acts as if he did until he exits the shot. In the following shot he holds the "uncaught" apple in his mouth.
When Senex kick's his wife's bust off the chariot, the statue's nose breaks off. In the subsequent close-up the nose lays right next to the statue's head, while in long shots the nose rests near the base of the bust.
At the entrance to the gladiator's training, the guard says suicide is against Roman law. Quite the contrary, as in modern Japan, in Ancient Rome, suicide was considered an honorable deed.
Lycas' toga is trimmed in purple; only Senators and youths were allowed to have purple on their togae.
By the time of the story the Romans did not practice human sacrifice. Even if they did Vestal Virgins would not be the ones to perform it. Rather it would be the Pontifex Maximus (High Priest)
Romans used three dice in their games, not two.
When Pseudolus water skis during the final chase, we can tell its a thinner stunt double because his clothes (which fit Zero Mostel so well), are loose. He has too much hair, as well.
The supposedly stone bier upon which Hysterium (disguised as Philia) is lying, jiggles when Miles Gloriosus leans on it.
In one song, Miles Gloriosus recounts his encounters with the Turks in war. The Turks would get nowhere near the Roman Empire as a military threat for centuries after the time depicted in the story. But the anachronism is simply the use of the word "Turks", because the Roman army fought frequently in Anatolia, which wasn't yet called Turkey.
In the middle of "Everybody Ought to Have a Maid," Pseudolus mouths the words, "giving out," but it's Senex's voice we hear.
When Lycus is displaying his goods, a sound man with recorder is seen in the background behind the African dancer.
When Gymnasia is introduced, a South American llama can be seen.