“In case” may seem familiar to Spanish speakers, but it’s not what it seems at first glance. In fact, we need to look at more of the phrase to be sure we know what we’re talking about.
By this, I mean we need to see if there’s an “of”, i.e., “in case of”. This phrase can be translated into Spanish, no problem.
In case of fire, break glass.
The barbeque will be outside. In case of rain, the auditorium can be used as a back-up location.
But, without that “of”, “in case” means “if something should happen”:
You shouldn’t light that match, in case you start a fire.
We’ve prepared the auditorium in case it rains during the barbeque.