Hawkeye's line "If I was a turtle, I'd be afraid to go into my own shell" led to the creation of the Franklin the Turtle books, illustrated by Brenda Clark.
It appears stock footage was used from 2 previous episodes that featured the bus. Quick shots from "Rainbow Bridge" and "The Bus" were both apparently used in the move to the cave.
When Margaret is preparing to drive back to camp, from the cave, Hawkeye says, "Drive slow. I want to read the Burma-Shave signs." Burma-Shave was a brand of shaving cream that was notable for its innovative advertising campaign. They would erect, usually 6, road signs in sequence along the nation's highways. Each sign displaying part of an amusing rhyme, ending in the products brand name.
In this episode, Margaret is terrified of loud noises. She never showed such fear before or after this episode. She implies that she takes care to hide her fear and not let it interfere with her work. She did show it when she and Hawkeye were trapped in the abandoned hut. Her fear led to them having a very brief affair.
Actually, the cave would be no safer than the camp unless it was not in the path/Target range of incoming fire, which was not the case here. The sounds of incoming fire and explosions seemed as close to the cave as they did at the camp. In fact. A hit on the cave could have caused it's total collapse, possibly killing everyone inside, or at least the collapse of the entrance, trapping everyone inside.