I've only seen this episode once on TV, maybe fifty plus years ago. I remembered the alligators, the rest was hazy at best. Glad I took the time to look it up here. Jack Benny was very special. Try to find him in the 1942 film 'To be or not to be' with Carole Lombard. It was before he turned 39 years old...
I always figured it would be difficult to create the complexities of the vault on television, but they really went all out to make the televised version pretty well live up to the elaborateness of the radio vault -- very cool!
Thanks for posting - the show is a favorite memory. I wondered if Mel Blanc would be the guard so he could have portrayed his classic line from radio: "Have they captured the Kaiser yet?"