The episode title shown at the beginning of the episode is "Hostage", but the title listed at the beginning of the end credits is "Hostage!" - with an exclamation point.
Black powder would not explode as depicted, unless constrained in some way. In an envelope it would, at best, flash over with a large amount of smoke. It might disorientation, but wouldn't kill.
Jody Collins sings the song "Cindy, Cindy", which wouldn't be written for another eighty years.
The word used for the marshy swamps of southern Louisiana is bayou, pronounced here as "bye-yew". Back then, and even today, it's pronounced as "bye-yoh".