Armageddon Now: Part 1 - S4-E13
Character mistake: Callisto's sword is missing. When she appears in the Xena Season Three finale "Sacrifice", her sword has reappeared. It is never explained why Callisto doesn't have her sword during her three appearances on Hercules the Legendary Journeys.
Answer: Most shows do flashbacks to show how things begin or what circumstances brought them to their current predicament. The modern episodes was to show how their legacies live on. Hercules changing his name to Kevin Sorbo and starring in a series about himself or Xena, her soul being reborn to continue her fight against evil.