Why Germany could not easily reinforce a failing Norway invasion

Could Germany have redirected forces from France to Norway if the invasion began to fail?

Probably not. Reinforcing the Norway operation after the opening move would have been nearly impossible.

The German move into Norway was a high-risk operation. Once it began to fail, reinforcing it would have been close to impossible. Diverting forces from France would not solve the basic problem of getting additional troops into the theatre. The campaign depended on surprise and immediate success rather than a deep reinforcement plan.