The "Continue..." function is a quick way to start workouts quickly. You don't have to use this button in order to start workouts, and you don't have to play each workout in order either.
To start a workout without using "Continue...", just tap the brand you're interested in (e.g. Zombies, Run!, Marvel, Venture), then find the series, season, or mode you're looking for.
There can be several reasons why the "Continue" list on the home screen may not be correct. This is almost always just a display issue however, and if your progress is backed up it won’t be lost.
We have designed our app so that you can start any workout you choose, in any order you choose, so if you want to you can start a workout from Zombies, Run! Season 4 without ever playing any from Seasons 1-3. There’s no penalty for doing this, and your stats won’t be adversely affected. If you'd like more information about mission order you can, check What Order Should I Play Zombies, Run! Missions In?