The title is a pun on the term "Achilles heel" which defines the weakness of an individual and is based on the story of Achilles that is described in Homer's Iliad. According to myth, dipping baby Achilles into a magical spring made him invulnerable - all but his heel, which his mother was holding. Achilles dies by being wounded in the heel by an arrow.
Valerie Mahaffey would later play alongside Kesley Grammer in Frasier (1993-2004), she plays his secretary in the episode Frasier: Maris Returns (2003).
Sam mentions to John Hill that Hill is the reason Sam is in therapy for the first time. This isn't necessarily true. In the beginning of season 3 when Frasier first appears, he gives Sam a few therapeutic sessions to help get over Diane.
Valerie Mahaffey also appeared in "CSI:Crime Scene Investigation" with Ted Danson and in "Kirstie" with Kirstie Alley.