Inspired by this question i wondered how many Dwellers can wait outside the vault. Even if there is no gameplay limit, what happens when more dwellers are waiting then can be graphically displayed because of limited space?
Imaging scenario, you have sent 25 dwellers for exploring and always accept on radio station or get some from lunchboxes without letting them in the vault. Now the 25 dwellers return but you already have 50+ new dwellers waiting in front of the vault.
What happens? There is no room to display 75+ dwellers outside of the vault (or wathever the limit is how many dwellers can be visible in the queue). Are they only not visible but still waiting outside? Or is there a limit how many new dwellers can wait outside? Has anybody tested this so far?