Keep Circulating the Tapes: Rescued. The first season was released on DVD in 2007, but due to presumably low sales never continued beyond said season and went out of print, done in by its distributor, Genius Entertainment, being folded into Vivendi Entertainment. In 2017, Mill Creek Entertainment announced they will release the complete series on DVD.
Retroactive Recognition: Jessica Alba as a rival to Alex for one of her crushes. Also Larissa Oleynik, who was really popular in the late 90's and early 2000's and still has somewhat of a career.
What Could Have Been: The original idea was for the show to be called "High Voltage" and to star a boy with special powers. However, when the series was pitched to Nickelodeon, it was decided that the main character should be a girl. And, thus, the idea was retooled into The Secret World Of Alex Mack.
It should come as no surprise that the decision to make the lead character a girl came at the same time that Nickelodeon was ending the network's most popular female-lead series Clarissa Explains It All.