When Selina opens her locket and looks at the picture of her mother, it is a picture of Julie Newmar, the original Catwoman from Batman (1966).
Frank Whaley (child-abductor Doug) is another Marvel/DC crossover actor. In the Netflix Luke Cage series he played Detective Scarfe in season one.
Angel Rosa is a Marvel/DC crossover actor. In this episode he plays the desk sergeant in the precinct. In Netflix's Daredevil season one he also played a police officer. In both shows he's listed as Cop/Police Officer #1.
The first two episodes of the series were broadcast simultaneously on both Veronica, the series' official broadcaster, and SBS9. However, for some reason this episode started about five minutes earlier on SBS9.