As a background ponyEdit
Derpy first appears in the first episode of the series in the background of several scenes and, as noted above, makes her googly-eyed appearance at Twilight Sparkle's welcoming party. She is mentioned by Rainbowshine and Rainbow Dash during Winter Wrap Up, using the name "Ditzy Doo", for flying the wrong direction for the second year running, trying to fetch the migrating birds back to Ponyville.
Derpy can be seen throughout the season trotting through a park, helping with storm preparations, participating in the Running of the Leaves, visiting Ponyville's market, and more. She is one of the ponies in the crowd who admires Pinkie Pie's "baked bads" in Applebuck Season. The shot pans over the crowd, and Derpy, Minuette, and Sea Swirl all mouth the line "Mmmmm...muffins" at approximately the same time. Derpy appears with intentionally crossed eyes in Feeling Pinkie Keen; when Twilight spies on Pinkie Pie, a series of objects falls on her head: a flower pot, an anvil, a cart of hay and finally a piano. A camera pan reveals that the items were dropped by Derpy and Sunshower Raindrops, who are hovering next to a movers' truck. In Green Isn't Your Color, she is heard gasping in shock at Fluttershy's catwalk antics.
As a Scripted characterEdit
Derpy appears in nineteen episodes of season one as a background character. For season two, she has gained a scripted-character status rather than an arbitrary background pony, and she is considered a "Where's Waldo"-type challenge for the fans. In the remastered version of the opening sequence that is first used in Lesson Zero, she appears in the top window of the first train car.