Dr. Selar, a Vulcan officer on the Enterprise-D, is frequently mentioned throughout the series, but this is the only time she appears.
This is the only TNG episode where a multi-person landing party is not made up at least one member that is 100% human. The landing party consists of Lt. Commander Data (android), Lt. Commander Troi (half Betazoid), Lt. Selar (Vulcan), and Lt. Worf (Klingon).
In a never-filmed scene in the script, Data was to have a bald head, mimicking Picard, after his Riker-like beard proved unpopular with Geordi and Deanna.
Dr. Ira Graves is the first of several Star Trek roles for William Morgan Sheppard. He would go on to play a Klingon Commander in Star Trek VI: The Undiscovered Country (1991) (the Rura Penthe Warden), Qatai in Bliss (1999), and the Vulcan Science Minister in JJ Abrams' Star Trek (2009) reboot.
The role of Dr. Ira Graves was written with Patrick McGoohan in mind. McGoohan starred in The Schizoid Man (1967) as part of his signature series.