Another week, another title of questionable relevance. "The Submarine Trap"? Okay, the submarine appears in it, and the Black Robes catch up with Crash, but...
I bought another book to quote from, but unfortunately, it turns out not to be useful. It's "The Republic Chapterplays," by R.M. Hayes. Oddly, none of the six Amazon reviews really describe the book: it's a 14-page introduction, followed by credits of the various Republic serials. No descriptions, no reviews, only occasionally a shred of extra information, such as the titles of sequels. It was originally published in 1991, but it's now superfluous in a world that has IMDb.
In the entry for Undersea Kingdom, we find this in the cast list (with their brackets): "Hakur Creighton [Lon] Chaney [Jr.]," meaning "the actor better known as Lon Chaney, Jr., was credited as Creighton Chaney here." Only he wasn't; as you can see below, he was credited as Lon Chaney, Jr. I don't know much about other Republic serials, but if I can catch an error that easily in the one I know about, I have to wonder about the general accuracy of the information.
1:15 Last week, the character cards seemed pretty specific. This week, they're just vague ones, and repeated from earlier chapters, at that. Was the title card sequence to this episode lost at some point, and filled in with title cards from a previous episode? Or did they just get lazy this week back in 1936?
5:02 Considering how upset the people of the Sacred City were about Crash accidentally breaking the little statue on the balcony, they sure let their big Poseidon go easily.
12:12 This isn't footage of the submarine sinking, played backwards. Honest. Just ignore the bubbles going down and back in through the exhaust.
17:03 Since their whole mission was to bring the priming powder back, this doesn't seem like an especially well thought-out plan.