The first time we Shane Casey he has an unkempt long beard. Later he is seen clean shaven.
(at around 25 mins) Sheldon says that rechargeable batteries are full of sulfuric acid. While that is true for an ordinary car battery and sealed lead-acid battery, the device in question is built to be light-weight and very likely employs a nickel or lithium based battery, neither of which rely on sulfuric acid. Then Sheldon and Reggie go on to crush the battery to release the electrolyte, which could cause a lithium ion battery to explode. (at around 40 mins) Sheldon also says that the reaction between sulfuric acid and metal releases hydrogen gas, and Reggie will not want to inhale it as it could kill him. In such a well ventilated space as in question, the small amount of acid would not be likely to produce a high enough concentration of hydrogen gas to be lethal.