The Creepy Candy Coating Corollary

In "The Creepy Candy Coating Corollary" Sheldon is seen drinking Red Bull - full strength no diet. In other episodes - notably "The Work Song Nanocluster" Sheldon is deeply concerned about drinking caffeine and that it may lead to narcotics.

The Gothowitz Deviation

In "The Gothowitz Deviation" Sheldon assures Penny that in an infinite number of universes none of the Sheldon's are dancing, yet in "The Agreement Dissection" he dances with all of the social graces required of "19th Century Vienna"