Colonel Raymond Chen wears a USAF Senior Airman rank insignia on his jacket sleeves. A Senior Airman is an E4 enlisted rank. A USAF colonel's insignia would be worn on the collar, not the sleeve. However since this is fiction & hypothetical, it's logical to infer (especially considering the shoulder flash on the character's uniform) that these could be rank insignia for a different agency, length-of-service stripes, or another type of insignia entirely.
When Lt. Lindy first retrieves the emergency case, he has to pull it up from the ocean depths, meaning it is not buoyant. When he jumps in the water with the case, however, it has become a flotation device.