The SQUID transistor is a reference to a superconducting quantum interference device (SQUID), which is a type of magnetometer used in magnetic resonance imaging (MRI), microscopy, oil and mineral detection, and gravitational wave detection amongst other uses.
This is the first time someone (Marcy) outright establishes by saying Aleksander is "The Historian".
In this episode the Viewer finds out the Director is an AI program, rather than a person.