David Boreanaz first got offered and passed on SEAL team after just coming off a long 12 year run on Bones (2005) but when it came back to him in hope he would change his mind, he decided to do it.
Tyler Grey, who plays Trent a.k.a Bravo 4, is a former US Army Ranger. He served in the 75th Ranger Regiment, 2nd Battalion as a sniper. Post Rangers he screened and was selected for Delta, AKA CAG (Combat Applications Group), a Special Missions Unit and the army equivalent of DEVGRU ( Naval Special Warfare Development Group). He was medically discharged after sustaining injuries from an improvised explosive device in 2005. His wounds are noticeable on his right forearm.
Over 75 US Military veterans have been hired for background characters and stunt work.
U.S. Navy SEAL Mark Semos wears many hats working on SEAL team: stunt man, consulting producer, actor but mainly he is a writer and has written several episodes.
The Special Patrol Insert Extraction (SPIE) system used by the blackhawk to rescue Bravo Team in Season 2 episode 21 was a first for network TV, it has never been done before on broadcast.