Wendy Makkena, who played IAD Det. Hitchcock, played Sasha Alexander's sister Dr. Rachel Cranston on NCIS (2003). The two were never on the show at the same time - Dr. Cranston appeared 6 years after the death of Alexander's character.
Maura has a red mug that says "Keep Calm and Buy Shoes;" in episode 5x12, "Burden of Proof," Jane mentioned that phrase as a guess for what poster hung in Maura's first apartment and Maura said she'd never heard it but that she liked it.
"Kent Drake" is in fact the surnames of multiple DC superheroes: Clark Kent (Superman), Connor Kent (Superboy), Jonathan Kent (also Superboy), Dinah Drake (Black Canary), and Tim Drake (third Robin/Red Robin). Clark Kent and Dinah Drake worked together in the Justice League for a very long time, and Connor Kent and Tim Drake worked together in the Teen Titans and are best friends (the Kents are related, the Drakes are not).
Jane says that Kent's name is the name of a superhero, and when Maura protests she says "Marvel superhero." Adam Sinclair, who plays Kent, had a role on Gotham; episode guest star LaMonica Garrett (IAD officer Simmons) had a major recurring role on all the CWs Arrowverse shows as The Monitor (a superhero); and both the names "Kent" and "Drake" are in fact the surname of multiple superheroes--all these superhero connections have to do with DC, though, the direct competitor of Marvel Comics.