Goofs

When Cusack and Chan decide to drop their swords due to the approaching sand storm, Cusack's character changes his sword grip from his blade pointed "up" to "down" twice.

The opening titles state that the events occur in 50 BC. Lucius introduces himself to Huo An as a representative of the Roman Empire. The founding of the Empire is generally set as 27 BC, when Octavian became Augustus Caesar.

Tiberius and his soldiers wear blue cloaks. Blue was considered a color of working class people. Blue was also considered the color of mourning, and the color of barbarians. The soldiers would have typically been wearing red or brown, although there was no official color for legionnaires. But they would not have worn blue. And Tiberius would certainly not wear blue. More likely purple.

In real history, Crassus invaded Parthia, and most of his army was destroyed. The film builds on the unproven notion that some Roman prisoners managed to reach China.

In an Action Fantasy movie with self-healing Romans and impervious Asians, the factoid that it was inspired by an unproven notion is not relevant as a Goof.

On 47:11 Jackie Chan gives a thumbs-up to John Cusack.