Since there’s not much solid wood in a hollow-core interior door, screws will usually tear out of the door as soon as any weight is applied to them. This complicates mounting items such as pictures, mirrors, hooks, etc. to the door. To mount anything into a hollow door requires special Hollow Door Anchors. These plastic anchors fold flat to fit inside a pilot hole drilled into the door. Once inserted, a small key is used to open the anchor, which spreads out interior brackets to clamp the collar of the anchor against the door face, like a toggle-bolt. The screw is then driven into the anchor until tight.
– M. Weber