For the book
- What Could Have Been: The book ends on a cliffhanger, suggesting a sequel, but one was never written as the author died 5 years later.
For the TV series
- Backed by the Pentagon:
- The US Navy allowed the production team to film scenes aboard the Arleigh Burke-class destroyers USS Halsey and USS Dewey as well as the USS Iowa museum ship. The destroyers were sailed several days out to sea so that the cameras could shoot 360 degrees without having to worry about coastlines, buildings, and other ships appearing in the background. Many of the sailors in the background were the crews of those ships going about their duties as cameras rolled.
- Season 2 episode "It's Not a Rumor" features a video recording of the real Secretary of the Navy, Ray Mabus.
- In Season 5, the US Marine Corps got involved and allowed for filming to be done during scheduled training exercises, resulting in some impressive amphibious assault sequences that the show would have otherwise not been able to afford.
- California Doubling: There are a lot of cases where you can obviously see the California coast in shots that are supposed to be in Norfolk, VA (which has no mountains within over a hundred miles) and the Louisiana bayou (which is even further from the nearest mountains than Norfolk and certainly doesn't have offshore mountainous islands). On the other hand, several areas in southern California do a pretty passable job as doubling as central Florida, and they found workable stand-in locations for Baltimore as well.
- The Cast Showoff: The script for Solace was immediately rewritten so that Wolf would run out of ammunition and have to take on a group of mooks barehanded when the writers learned that Bren Foster is a world champion martial artist.
- Creator Backlash: Rhona Mitra wasn't happy with the way things ended for her on the show so the showrunners decided against asking her back to avoid any more hurt feelings.
- Creator Breakdown: Production of Season 5 had to be put on hold as Eric Dane took time off to seek treatment for clinical depression.
- Descended Creator: Peter Weller is one of the show's regular directors and also played the role of Paul Vellek during Season 4, even directing himself in a couple of episodes.
- Distanced from Current Events: The season three premiere was pushed back a week after the Orlando Nightclub Mass Shooting, as the episode contained a mass shooting in a Vietnamese nightclub. Ironically, the scene in question had already aired twice two weeks earlier, as part of both a five-minute sneak peek of the season and when the first half of the (two-hour) premiere was televised after the Western Conference Finals
- Fake American: Tex is played by the Australian-born Canadian-raised John Pyper-Ferguson.
- Fake Nationality: British Immune Sean Ramsay is played by Irish actor Brian F. O'Bryne.
- Fake Russian: Averted for once. Ravil Isyanov was born and raised in Russia—and even served in the Soviet Air Force!
- Post-Script Season: The primary Red Flu plot is wrapped up by Season 3, with the virus under control and the US beginning the process of reestablishing itself. Season 4 struggled to continue the concept with the Red Rust storyline while Season 5 let go of the global pandemic story to focus on the ongoing geopolitical fallout of the collapsed world order.
- Promoted to Opening Titles: John Pyper-Ferguson and Jocko Sims joined the main cast in Season 2 after recurring in Season 1.
- Real Life Writes the Plot: Tex only regularly appears in the first two seasons because John Pyper-Ferguson wanted to have the flexibility to pick and choose projects as he pleased. His limited return only came about as a result of the showrunners begging him into a handshake deal.
