At the 45:48 mark, kazuma and megumin hear an alarm outside announcing that the devil kings army is attacking and they run out to investigate, although they shouldn't have been able to get out of the room they were in since the door was locked from the other side and the window was frozen shut.
(Forgot to mention that Kazuma can use magic but is lazy?)
(Forgot to mention that Kazuma can use magic but is lazy?)