How to erase any residual keyframes from a .blend file? This is something annoying because it always happens at some point, since I know Blender in version 2.5x I have always wondered how to delete those keyframes that are lost and do not appear or are assigned to any object or value or constant of your blend file, and that you never find and although they seem harmless they always end up causing you problems to export your model to some other game engine platform.

Any suggestion of how to erase these keyframes? Some script or something in the file that you should delete???

empty.blend download
I got rid of it but using vers 2.77a.  Let's hope it works in your version...

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The problem was a grease pencil hangover and it's slot that was still active.

Procedure to rid yourself of that pesky keyframe...

Zoom in a bit to see the G/pencil drawing south of the grid.

Goto Edit mode and press A.  The GP points will all hilight

Delete them with X.  (points)

Press N to open the 3D viewport's properties and delete the Grease Pencil slot.

Untick the grease pencil's box.

The keyframe will still be there.  

Save the file as something else and the keyframe should disappear when the 3D widow updates.

If not exit Blender and reload.