You need to bring the squad back to shelter before the 23 pm, it's a rule of the game, you can't travel around after 23 pm, you need to get back to shelter before this or you will be a punish.
Before this I was thinking that if your squad is outside 23 pm, you will be attacked by the night creatures, you die, and you will get a game over.
Even if your squad is inside if you forward the time and it's got to 23 pm you are punished losing morale.
But if this is happening before 23 pm, it's bugged.