Colleagues I currently and have previously worked with add some of the following:

-Map out the timing of the entire concert
-Incorporate set changes if there are any students that move spots within the ensemble.
-Soloist/featured player acknowledgement
-Invitations to administrators
-Backup concert attire (if concert black or tuxes, have extra socks/ties on hand)
-If concert is in a different location than rehearsal space, have an instrument repair go-bag for emergency repairs (Valentino pads if you have a set, valve oil, flathead screwdriver, something to manipulate woodwind springs)
-Make sure you have all your scores, maybe even a backup baton (maybe speaking from experience)

There are more but the rest are escaping me at the moment