Unlock Epilogue: When you find ALL 60 puzzle pieces and complete the jigsaw puzzles on every World the broken ladder that leads to the attic in the house where levels are selected will now be fixed. Climb up and enter the door to access World 1. Complete World 1 again to see the Epilogue. If you want to revisit the Epilogue at any time you have to walk into the hidden alcove on the left side of the 'Title' screen.
Unlock Alternate Ending Sequence: The last secret star in the final level becomes unlocked when you collect the first 7 secret stars. Several of the switches in the final level will no longer be affected by time manipulation allowing the last secret star to be collected and changing the ending.