Keesha Bush-Trenerry voices Rainbow Dash in Episode 1, and Diamond Tiara's mom in Episode 4 (even though Diamond Tiara's mom wasn't seen).
Ashley Rits voices several background ponies in the opening of Episode 2, with phrases like "Cloud!" and "Fly!" (happened to be said by Pegasi getting ready for the thunderstorm) In Episode 3 she is listed as "Cherry Pony".
Brony Mike plays a filly in Episode 4 who says "I just follow the crowd!" He also covers several FiW songs on his channel.
Ian Colby voices Dr. American - a spoof of the Dr. Whooves fanon in which his only line is "I'm American."
FiMFlamFilosophy can be heard saying "Hello there, ladies" during the party in Episode 4. This is an excerpt from the Scootaloo audition he sent to Sherclop. It is noted that he works on a MLP parody named Rainbow Dash Presents.