Upon learning that the victim has an identical twin, Castle calls the fact that he wears glasses "the worst disguise since Clark Kent". Stana Katic and Molly C. Quinn both appear in Superman: Unbound (2013), as, respectively, Lois Lane, Clark's love interest, and Supergirl, his cousin from Krypton.
When Lanie picks up her phone at the beginning of the episode, she's looking at it upside down.
One of the suspects of the episode is a wheelchair-bound man. Beckett humorously makes reference to Professor X. Professor X/Charles Francis Xavier is a comic book character, the wheelchair-bound founder and mentor of the X-Men. He was introduced in X-Men vol. 1 #1 (September 1963), created by Stan Lee and Jack Kirby.
Dan Castellaneta had previously appeared on the series as Judge Markway.