Medics are enlisted personnel, not officers. Lt. Tamara Johansen should be a nurse or doctor.
With the exception of one character with blood stains on his shirt from a wound in the first episode, and an occasional smudge here and there, none of the characters' clothing seems to get dirty. Because water is limited and must be reserved for drinking and cooking, it can't be used for cleaning clothes.
There is no mention at any time of how their clothing is being cleaned.
In fact, the characters' clothes look constantly dirty and dusty (not just the occasional smudge) and the patterns of dirt/dust remain constant throughout, no mean feat for the wardrobe department.
Hunter Riley cannot have the rank of Sergeant. The Air Force eliminated the rank of Sergeant in 1994. By the number of stripes on his collar insignia, his correct rank should be Senior Airman.
Lieutenant Scott and Master Sergeant Greer are portrayed as having the same cultural references and being about the same age: however, in reality, a Master Sergeant would be at least 12 years senior to a First Lieutenant.
TJ is called a medic. However, she's a military officer and could not hold that designation.
If she was a lieutenant, she would be a nurse or a nurse practitioner.