 Millie Bobby BrownMichelle | Michelle |
 Chris PrattKeats | Keats |
 Ke Huy QuanDr. Amherst / P.C (voice) | Dr. Amherst / P.C (voice) |
 Jason AlexanderTed / Wingman | Ted / Wingman |
 Woody NormanChristopher | Christopher |
 Giancarlo EspositoColonel Bradbury / The Marshall | Colonel Bradbury / The Marshall |
 Stanley TucciEthan Skate | Ethan Skate |
 Woody HarrelsonMr. Peanut (voice) | Mr. Peanut (voice) |
 Anthony MackieHerman (voice) | Herman (voice) |
 Brian CoxPopfly (voice) | Popfly (voice) |
 Jenny SlatePenny Pal (voice) | Penny Pal (voice) |
 Hank AzariaPerplexo (voice) | Perplexo (voice) |
 Colman DomingoWolfe (voice) | Wolfe (voice) |
 Alan TudykCosmo (voice) | Cosmo (voice) |
 Ann RussoMom | Mom |
 Greg CromerDad | Dad |
 Vince PisaniScience Professor | Science Professor |
 Camrus JohnsonCorporal Carson | Corporal Carson |
| JJuan Uribe BrandiUniversity Student | University Student |
 Kurt LoderKurt Loder | Kurt Loder |
| RRoshni EdwardsJessie | Jessie |
 Holly HunterMadeline Vance | Madeline Vance |
 Will LymanDocumentary Narrator (voice) | Documentary Narrator (voice) |
| AAubrey BrockwellMilkmatic Girl | Milkmatic Girl |
| CCamille MarquezBeachgoer / History Teacher Drone | Beachgoer / History Teacher Drone |
 Tuc WatkinsArthur Meadows | Arthur Meadows |
 Billy GardellGarbage Bot (voice) | Garbage Bot (voice) |
 Merle DandridgeNews Anchor | News Anchor |
| IIan McShaySoldier | Soldier |
| AAnthony J. VorhiesStaff Sergeant Stanisic | Staff Sergeant Stanisic |
