Same here, bend the backing sheet and the edges of the masks will appear.In the end I bent them gently in a curve to create a slight gap and then gently used a scalpel blade to lift them off.
For the canopy, I would try gluing it back together with Pledge or with a clear-setting PVA glue. If that doesn't work you can soak it in water to remove it and try something else - you have nothing to lose!
Pete