==Realism (submitted for possible addition)== 

 (I don't mean to take away the fun if you elect to suspend disbelief, but wikipedia is supposed to be informative.) 

 Like most action movies, the premise of this movie is highly implausible.  If 500 snakes were released in a plane's cargo hold, it is unlikely that a single one would encounter passengers.  Snakes are poikilothermic, and in a low temperature like a cargo hold (typically 50–70°F, or 10–21°C), will be slow or torpid and unwilling to travel.  Snakes are even shyer than usual when in unfamiliar territory, such as a strange-smelling cargo hold.  They would also find the constant vibration unnerving; although they lack external ears to hear sound, they have fully functioning internal ears and are very sensitive to conducted vibrations.  With difficult-to-climb aluminum walls and a mostly solid ceiling underneath the passenger cabin further to discourage adventurism, the snakes would simply find small enclosed spaces to hide in until the situation got better.