Author Filibuster: There is, at one point, a rant about how the pharmaceutical industry giants and the Bush administration may be responsible for the virus and/or seek to profit from the vaccine. It's delivered by an unreasonable Strawman Political conspiracy theorist.
Badass Family: The protagonists. Dad is a former special forces soldier, both daughters (particularly the younger one, Faith) mercilessly slaughter entire herds of zombies, and mom is an engineer that keeps things working in spite of resource limitations imposed by the setting even if she doesn't herself participate in zombie slaughtering
Bury Your Gays: A gay cop is introduced, given some backstory and then killed. What happens to his husband is unrevealed but considering he's in the middle of a zombie apocalypse, his chances aren't good.
Chainsaw Good: During the operation to clear a cruise line ship, Faith mentions several times that she'd like to have a chainsaw available as a clearing tool, although Fontana points out some of the problems with using a chainsaw as a weapon.
Crazy-Prepared: The Smith family have enough plans for different apocalyptic scenarios, with a codefor every single one of them. The father also has at least one other identity ready in advance, which he uses to keep the preparations for the apocalypse from being tracked back to him.
Groin Attack: In a discussion on how to deal with infected security people aboard a cruise liner who are wearing body armor, Faith suggests a chainsaw. When Fontana points out the Kevlar armor would jam the chain, she says "come up", and makes a motion of cutting up between the legs.
Hate Plague: H7D3 ultimately turns the infected into feral, vicious non-sapient cannibalistic animals who are human only in a biological sense.
Human Resources: The fastest way of collecting large amounts of antibodies for use in a vaccine against H7D3 is to collect the fluids from the head and spine of its victims, as it only infects higher level primates. The task is done under secret conditions by Thomas Smith and some associates due to the illegality of the act.
Jurisdiction Friction: The FBI is mentioned several times as making it difficult to track down the virus, as the microbiology experts supposed to be assisting them are also the primary suspects, and the FBI's concern is more "find the guilty party" than "stop the virus". CDC staffers are particularly hostile to the FBI, thanks to how they reacted to previous events like the anthrax attack shortly after the September 11, 2001 attack.
Little Miss Badass: Faith becomes well known, both in the story and out, as being a hardcore ass-kicker, at all of 13 years old.
No Celebrities Were Harmed: At one point the team salvages a luxurious yacht belonging to "Mike Mickerberg", the CEO of "Spacebook", recognizes the owner among the zombies, and promptly serves him with a 12 gauge round.
Not Using the Z Word: Given that zombies were previously regarded as purely fictional, the experts are initially reluctant to call victims of H7D3 "zombies", but eventually give in to the inevitable as everyone's thoughts gravitate that way anyhow.
Sanity Slippage: Faith goes a little into this after they board a yacht that was taken over by the mercenaries hired to protect it and sees the carnage that followed, killing and rape everyone there. It becomes more serious when they're clearing a cruise ship later. Oddly it's not fighting zombies that does it but what she finds after the zombies are cleared out, the horror shows in the cabins, even the ones where they find survivors. She turns Trixie, a teddy bear they found on one ship into a Companion Cube as a coping mechanism.
Schmuck Bait: One of the methods Wolf Squadron uses for dealing with zombies, discussed in Graveyard Sky and used in Darkling Sea, relying on the fact that zombies are attracted to noise and lights. Both done on a group level (ships holding large parties before machine gunning down zombies) and automated systems (modified cargo carriers turned into zombie shredding machines).
Synthetic Plague: H7D3 is a purposefully designed multi-stage agent that ultimately turns its victims into very aggressive humans with no real sapience, basically being little more than two-legged feral animals.
Vestigial Empire: Many governments and their militaries, after the Hate Plague hits them, are almost totally destroyed, ruling only a relatively small part of their original territory.
The Cameo: Voltaire shows up in the midst of an apocalyptic rave in the Central Park.
Would Hurt a Child: Many people comment on the fact they don't like killing the zombie children and while we don't see it happen the characters clean up the remains of children on occasion.