How do you see which of your reservations (or bikes) are currently checked out?

use the 'stage' button to search for all reservations in the 'checked out' stage:

This will return you a list of all reservations currently in that stage.  Then you'll quickly be able to see which if any are due back, or late.

*N.B. soon BRM will automatically flag up late reservations.  (Spring 2016)