Hodgins says they'll name the child Michael Joseph if it's a boy or Katherine Temperance if it's a girl. Michael Peterson wrote this episode, and Joseph is Booth's middle name. Also, Joseph Michael are real names of Dusty Hill, the other long-bearded member of ZZ Top band. Kathy Reichs is the inspiration behind Bones, and Temperance is Bones' first name.
Angela is looking at a picture labeled, "AM-40 Rifle"; Brennan says, "This bullet has a diameter of 25 millimeters; the diameter of the bullet we recovered is 20 millimeters." These have actually existed as experimental prototypes, though they're called "airburst grenades" rather than "bullets". The picture looks like the Barrett XM109, developed in the late 1990s, which fired projectiles 25 mm in diameter. Other examples include the XM29 OICW (20 mm) and XM25 CDTE (25 mm). The prefix "X" indicates experimental or prototype status. All three of these used projectiles which could be set to explode at a particular distance.
First episode where Cam has her "Karen" haircut.