You can—and should—include foreshadowing in your story.
It's good for your readers to look for hints and try to decipher them.
However, when you're creating a new world, you have to make sure your hints can be understood and processed in order for them to be remembered.
Don't talk about the qualag machine being lost if you never explain what that machine is or what it has the potential to do.
Don't place a stunner gun that has a secret feature to revive people and only reveal this extra feature when it's being used to save the day.
Foreshadowing is great, but if you're creating a whole new world, make sure your foreshadowing can be understood and doesn't feel like a convenient miracle when most needed in your story.