Otto: Whoa, that changes everything!
— "Disorder in the Court"- Otto summing up most of the moments on the page.
Odd Squad is a far cry from your average PBS Kids program of the current era. In addition to the typical educational value, this show has serialization and Story Arcs. So naturally, there are going to be certain episodes that change the flow of the show as we know it.
Season 1
- "Totally Odd Squad". Ms. O (Oprah) tells the story of how she became an official Ms. O. '80s Ms. O pretended to be a villain called "The Patternista", and she and O'Donahue set up a fake villain-capture scenario as a test to see if Oprah was smart enough to follow the clues and take the job of Ms. O. Oprah was able to find the warehouse the two were in and became the new Ms. O.
- "Fistful of Fruit Juice" Ms. O explains when how she first joined Odd Squad.
- "Training Day" is the first episode to be taken completely seriously. It reveals that Odd Todd was Olive's old partner; also, Olive's afraid of pies because she had to shut down a Pie-nado Odd Todd released after he turned evil..
- "Oscar of All Trades", Oscar reveals he had and was fired from over 60 different Odd Squad jobs before he became a scientist; also he invented the Odd Squad Science Department.
- "O is Not For Over", where Olive and Otto leave.
Season 2
- "First Day". Olympia and Otis join Odd Squad and become the new main heroes of the show. Olaf is actually a werewolf.
- "Oscar Strikes Back". Oscar leaves Odd Squad.
- "Dr. O Party Time: Excellent". Dr. O leaves Odd Squad to work at a space station.
- "Xs and Os": Xena and Xavier, a special division of Odd Squad, are introduced.
- "Dr. O No": Agent Oro officially becomes Dr. O's replacement doctor for Precinct 13579.
- "Who Is Agent Otis?". Otis's backstory is revealed and he was actually raised by ducks and used to be a villain, before he felt guilty, called Ms. O stop his duck family, and was trained by Ms. O and joined Odd Squad. Also to Otis and Oprah are temporarily fired
- "Odds and Ends". Ohlm is actually an evil mastermind who pretended to be a idiot, and sold out Odd Squad and gave villains some plans to break in. As one would expect, Olympia, Otis, Oona and Ms. O were all surprised that Ohlm out of all people was a traitor to Odd Squad. It's even the current image for this page. After Ohlm gets defeated by Otis, he's grounded by his parents, and kicked out of Odd Squad, resulting in not only Otis getting rehired, but the Big O stepping down to go to kindergarten and Oprah taking his place, with Orson replacing Ms. O.
Season 3
- "Odd Beginnings": Opal, Omar, Orla and Oswald all join forces to find and save the legendary 44-leaf clover. Once they succeed, they are promoted to the newly-formed department of Mobile Unit, traveling the world to solve cases. The Big Bad of the season, The Shadow, also makes her debut.
- Oprah is revealed to have the capability to control how she ages, putting many fans' theories about how aging in the world of Odd Squad works to rest.
- "Slow Your Roll". The Shadow sets her first evil plan into motion: hacking into the van and sending it barrelling towards the Lake of Goo, with OSMU still inside. It also reveals that The Shadow and Opal have some sort of personal connection with each other.
- "Odd in Sixty Seconds". Following "Slow Your Roll", The Shadow gets to work on her ultimate plan: building a Villain Network of every villain known to exist in Odd Squad history. She begins by breaking into the organization's top-secret facility, stealing information on all of the villains (as well as Opal), and making an easy escape back to her Supervillain Lair.
- "Villain Networking", the Sequel Episode to "Odd in Sixty Seconds". With the information she has, The Shadow attempts to bring all of the villains together into her Villain Network. After many trials and tribulations with the villains blaming each other for a decline in oddness, she eventually succeeds.
- "16-and-a-Half Blocks". Opal, Omar, Orla and Oswald bring Evil Sculptor, a villain who wishes to perform a Heel–Face Turn and defect from the Villain Network, to an Odd Squad safe house located in Toronto. At the end of the episode, the group make it before other villains in the Villain Network can capture them, and Evil Sculptor tells the Big O about The Shadow's ultimate plan.
- "Follow the Leader". The Shadow's true identity is revealed as that of Olizabeth, Opal's younger sister.
- "End of the Road". The Shadow begins to bring her plan of releasing all of the villains' powers into precincts around the world to fruition. However, after a heart-to-heart talk with Opal, she performs a Heel–Face Turn and gains an ally in the form of the Mobile Unit. At the end of the episode, Opal decides to leave the Mobile Unit permanently in order to stay with her sister and help her fix the damage she's done in Australia and in other countries.
