Factual error: One of the naked female dancers at the party has breast implants. Although some forms of plastic surgery were known to the Romans, breast augmentation was not one of them. If you want to check for yourself she appears just after the masked dwarf moves through the shot.
Factual error: During the final battle as Saxa starts using the ballista against the Romans in the front, the ballista is portrayed as a weapon launching multiple projectiles at once, while in reality it only launched one at the time.
Other mistake: In the scene where Barca is bleeding at the pool, Batiatus comes and grabs his hair. Barca abruptly moves before Batiatus starts to actually pull his hair.
Mark of the Brotherhood - S1-E8
Continuity mistake: Near the start, right after Spartacus slices a man, you see him holding only the hilt of a sword - when shots of cutting are seen, the blades are normally added digitally, but it wasn't in this case. A couple of seconds later it is back to a full sword. (00:01:40)
Factual error: When Numerius wants Spartacus to kill Varro, he gives a thumbs-down. People who wanted to see a defeated gladiator slain would express their desire with a thumbs-up gesture instead.
Factual error: When Lucretia is attending the market she is wearing high heel shoes which did not exist at the time, and weren't invented until the 15th century.
Revealing mistake: During the final battle there is a dual between Julius Caesar and Gannicus. At one point Gannicus spins Ceasar around and he is shown to wear modern day underwear.
Continuity mistake: During the final battle there is a long trap between the armies, filled with spears and hidden, where the Romans fall when trying to get to Spartacus' army. Before the Romans pass into it, a messenger from the Roman army comes through on his horse without falling into this long continuous trap.
