During the sword fight between Grey and the commandant, a few shots show that the stuntman filling in for Darren McGavin has a much narrower face and pointed chin.
Per the opening narration, this episode occurs in 1843. Ben notes that Grey was recently fooled by several female passengers. Later, Grey mentions Ellie Jenkins and Laurie Sutton, who appeared in episodes 4 and 7, respectively. However, Episode 11, "The Boy From Pittsburgh," takes place in July 1841 per the opening title card. If episodes 4 and 7 occurred before episode 11, then they can't have happened recently as Ben claims.
Ben: Well, how do you expect me to get there? I've never navigated across open water like that before.
Grey: You'll learn. I'll buy you a book in New Orleans.
Ben: Well, what's going to hold the boat together?
Grey: Chicken wire and light twine!