The homeless vet Ray talks to has a tattoo on his arm that has a unit insignia and says "Big Red One", Ray tells him they might have worked together in Ghazni back in 2012 (Operation Enduring Freedom XIII). Big Red One is the official nickname for the United States Army's 1st Infantry Division, as the nickname implies their unit insignia is a red "1". The 1st was formed in 1917 during World War I and is the oldest continuously serving division in the Regular Army. Based out of Fort Riley, Kansas the 1st has participated in every war and major military operation of the past century, they saw heavy fighting post 9-11 during the Iraq War, especially in the First and Second Battle of Fallujah; they also saw a lot of action in Afghanistan during Operation Enduring Freedom and Freedom's Sentinel. The 1st also participated in the joint international military intervention against the Islamic State in Iraq and Syria in 2018 known as Operation Inherent Resolve.
Special Boat Service (SBS) is the special forces unit of the United Kingdom's Royal Navy, they serve as the maritime special forces unit of the UK military and focus on counter-terrorism and special operations. They are a sister unit to the UK's other Tier One equivalent unit the British Army's 22nd Special Air Service Regiment (SAS), operations conducted by both the SAS and SBS are highly classified and never commented on by the British government, hence very little is known about their structure and how they operate. However the SAS and SBS regularly work joint ops with the US military's Tier One SMU's like Delta Force, DEVGRU and 24th STS (Special Tactics Squadron), so their operational structure and tactics are likely very similar.
Sonny's ironic fear of water once again emerges, he says he doesn't want to go into the river because he heard piranhas have been found in it. Sonny likes to be dramatic about being in water, he complains about being eaten by sharks even when they are in parts of the ocean where sharks aren't found, likewise here he is worrying about piranhas when they are on the other side of the planet from their habitat. Piranhas are only native to South America, specifically in the Amazon River basin; however piranhas have been introduced into a few other areas by humans, but only two areas outside of South America have had confirmed piranha sightings: the Lihang River in China and Kaptai Lake in Bangladesh. Sonny can relax as they are about 3,200 miles from the nearest piranhas.
Graduates of SEAL Qualification Training (SQT) receive the "SEAL Trident" or "Special Warfare insignia", which has an eagle incorporated into design, to signify that they are a Navy SEALs. When an operator "get his bird pulled", they are removed from the team and cast-off to regular Navy for reassignment.
Tyler Grey, who plays Trent, was medically discharged after sustaining injuries from an improvised explosive device in 2005 while he was in the Special Military Unit known as Delta Force. His wounds are noticeable on his right forearm.