The only time I ever had a large piece like that missing, it was pretty clear (on afterthought) that the box had been opened in the store before I bought it.
And I've had to return a set or two to Amazon because they'd clearly been opened and returned (and usually all the minifigs stripped out).
And I've had to return a set or two to Amazon because they'd clearly been opened and returned (and usually all the minifigs stripped out).