Holder's girlfriend (played by
Jewel Staite) makes a comment about his chest tattoo, which spells "Serenity". This is a reference to the Sci-Fi show _Firefly (2002-2003)_, where Staite's character is the mechanic on a spaceship called "Serenity". Staite's character in _Firefly_ is called Kaylee, which is similar to the name of the missing girl, Kallie.