Keith and the rest of the Voltron Force catches on to Planet Doom's scam relatively quickly, based on their experience with Witch Haggar's spells and Lotor's obsession with Allura. Ironically, in the original GoLion episode this is based on, Kogane (Black Lion Pilot/Leader) and the GoLion Team fail to catch on until they see the lengths their enemies Honerva and Sincline (Witch and Prince) are willing to go to get the supposedly dead body of Farla (Princess). Usually, the darker tone of the original anime means that the heroes of GoLion are more savvy than their Voltron Force counterparts.
The woman who resembles Allura from Lotor's dream and in Haggar's image happens to be Allura's mother who was captured and killed by Zarkon. It is unknown how Lotor knows Allura's mother in his dream.
Because it's one of the very few episodes the lions don't form Voltron, Voltron does not appear in this episode.