| Cast overview: |
 | Jim Carter | - | Himself - Narrator (voice) |
 | Hugh Hunt | - | Himself - Lead Engineer (as Dr Hugh Hunt) |
 | Arnie Schreder | - | Himself - Pilot, Buffalo Airways |
 | Mikey McBryan | - | Himself - Manager, Buffalo Airways |
 | Mary Stopes-Roe | - | Herself - Daughter of Barnes Wallis |
 | Rick Donnelly | - | Himself - Dam Designer |
 | Sidney Alford | - | Himself - Explosives Engineer (as Dr Sidney Alford) |
 | Alfred Breland | - | Himself - Dam Co-Designer |
 | Jim Bellavance | - | Himself - Dam Construction Engineer |
 | Tod Todeschini | - | Himself - Launcher Designer |
 | George 'Johnny' Johnson | - | Himself - Bomb Aimer, 617 Squadron (as Johnny Johnson) |
 | Ryan Beaubien | - | Himself - Aeronautics Engineer |
 | Hilary Costello | - | Herself - PhD Student |
 | Chuck Adams | - | Himself - Maintenance Engineer, Buffalo Airways |
 | Alex Wagner | - | Himself - Co-Pilot, Buffalo Airways |