Objects in the cockpit can certainly cause you trouble, even the seemingly most innoxious.
Chap flying a Bell 212 helicopter had placed his pencil on the centre console, upon lowering the collective it caught the pencil which had vibrated so a portion was hanging over the edge of the console, the console edge acted as a fulcrum and the pencil was caught under the fuel governor switch (a latched switch that had to be lifted to move past a detent), lifting it out of AUTO into MANual, which of course then lead to a massive overspeed and hence trashed engine.
The following video accident was caused by an IPad that was dropped and jammed the pedals, fatal to the crew.
