During the final battle between Auctus and Crixus, a man is heard singing in Arabic as Auctus is being thrown up against a wall. A loose English translation for this is, "My life is over."
When Gnaeus (Raicho Vasilev) fights Barca in the arena, he fought in the style of Thraex (characterized by his weapon and shield.) Thraex was a style modeled after the soldiers of Thrace; which would become modern day Bulgaria. Raicho is from Bulgaria.
The armor that Oenomaus wears after becoming Doctore has a patch beneath the left breast. This is where Oenomaus stabbed the previous Doctore during their fight. From this episode and in the previous episodes of Gods of the Arena the patch is there as a reminder of this right of passage. This patch was visibly present during the season "Blood & Sand."
Gannicus has a small tattoo on his neck that wasn't there in the first two episodes.