A puzzling situation

At the beginning of the summer, I thought it would be fun to put a puzzle together. We bought a puzzle from the Dollar Store (because that is where we were when I had the idea). Over the past few weeks, we have been working bit by bit on the puzzle. Today, we finished it! Hooray! After the first step of assembling the borders, we realized that we were missing a piece. We had hoped that it would be found by the time the puzzle was completed. However, much to our frustration, the missing piece did not make an appearance. We have a sneaking suspicion that whoever boxed the puzzle left the piece out intentionally. That's what I would do if I was a puzzle boxer!