Giant lizards. If in doubt go for giant lizards, they're a classic.

Bonus points if, instead of a miniature, you use a tablet looping several stock footage clips of a normal lizard.

For a plot? There's a town near a dessert where people are mysteriously vanishing, but the only part of their cars that disappears with then I'd the roof. The reason? Giant dessert lizards. Cone on, you know you want to, you even know all the stock characters.