This is the last episode to feature the original four cast members from the beginning of the series, consisting of Christopher Meloni, Mariska Hargitay, Richard Belzer, and Dann Florek.
When Stabler is accused of molesting Hunter, Ed Tucker comments that Stabler has possibly been on the job too long, and then cites Friedrich Nietzsche's quote "Those who fight monsters be careful lest ye become a monster." Ironically, the same line is used by Lauren Cooper in season nine's Signature (2008).
In the opening scene, the date tells Annie Meyers that if one is a Republican before age 30, then they have no heart, but if they are a Democrat after age 30, they have no head. This was inspired by a quote often attributed to Winston Churchill: "If you are not a liberal at twenty, you have no heart. If you are not a conservative at forty, you have no brain."
Sterling Beaumon (Hunter), also plays a very similar character in the Criminal Minds (2005) episode Safe Haven (2010) (2010). His character in that is more of a sociopath but also mostly goes after mother figures, although in that they all have kids too.
MRIs always produce a magnetic field. When the detectives entered the MRI area anything metal would have been violently attracted to the machine.