When the new set of guards arrived to replace those who had watched over Peter during the last section of the night, they discovered their fellow guards asleep with Peter having escaped. The guards who are woken up have no recollection of what has happened and there is a lot of commotion as a result. The Roman guards would be frightened because they know that their life is forfeit if a prisoner escapes (see Acts 16:27; Acts 27:42).1
18 Now when day came, there was no little disturbance among the soldiers over what had become of Peter.