When Gannicus and Oenomaeus square off at the execution, each man manages to disarm the other of a sword. Gannicus ends the fight by kneeing Oenomaeus in the face and stands over him ready to strike with his remaining sword. However when the camera shot pans out to capture both men, Gannicus is again holding two swords without having retrieved his second.
Ilithyia didn't need to conspire with her father to gain a divorce from Glaber, Roman aristocrats of that period engaged in 'Free Marriage' and either party could end it at any time. She was perfectly within her rights to just tell him he was divorced.