In the final scene, Ethan sees a photo of himself in uniform and says it was taken on his first day in the Navy. In the photo, he has four rows of award/medal ribbons and a surface warfare badge. He would have, at best, a single National Defense ribbon on his first day of military service.
Bulbar onset ALS is considered the most severe variant of the disease. It starts in the bulbar region of the brain that controls muscles in the face and neck, which in turn affect speech and swallowing.
10% of ALS cases can be traced to genetics, there are tests for those who have someone in their family who died from the disease but it doesn't always appear on the chromosomes tested. 90% of ALS cases are sporadic. 25% of ALS cases are bulbar onset, while 75% are limb onset.