- Crowning Moment of Heartwarming: In the episode Sheena was introduced in, Marc has spent the entire episode trying and failing to get her to notice him, even going as far as using a WOOHP gadget to alter his appearance, which also fails. Towards the end of the episode, Marc decides he's going to try one more time and plans on using the gadget again. Megan (who had been encouraging the entire time and trying to convince Marc that he didn't need to change to get Sheena to like him) begrudgingly approves but insists that Marc let her set his appearance. He agrees and for the rest of the scene, Marc's face is obscured. After Sheena says yes, Marc goes back over to his sister and tells her that whatever look she gave him sure worked. Megan holds up a mirror...and reveals she just set his looks back to normal.
Marc: No way...Megan: (affectionately) For a genius, you can be pretty dumb sometimes.
- Headscratchers: In 2 of the Missing Episodes, someone (Trudi and Tami to be exact) are turned into spy-sassins by a gadget the Spiez had lying around that was issued by WOOHP...why would you have something like that and in Trudi's case, why would they bring it home with them?
- In the episode that introduced Sherry, why in the world didn't Lee, Megan and Tony notice that Marc was acting brain-dead after his first session with her? Megan especially has no excuse given how close she and Marc are.
- In the first episode, Tony is scolding for "playing video games" on the job before revealing that he's using the gadget to drive. Since none of the Clarks are old enough to drive in either Canada or the USA, this probably is a common occurrence so there shouldn't have been reason to be confused.
- Meaningful Name: Technical example; Marc's name is spelled the same way as the MARC system for library online catalogs. Given his position as The Smart Guy, it's appropriate.
- Les Yay: In "Operation Yeti Bear", Megan seems to be quite enamored with athletic prodigy Tara Prefontaine...
Megan: Wow! That is one fantastic girl!
- Series Continuity Error: In "The Spy Sitter", Marc asks for something that includes meat. However in "Pet Peeved", Tony stated that Marc is a vegetarian. Now that could have been a development between the episodes or Tony just trying to distract their attacker but clarity would have been nice.