When Suzie is tied up in the back of the van, the rope changes position from around her arm, to over her shoulder, back to around her arm.
When the Red F-150 gets towed from out in the desert, the shot inside of the tow truck shows a gray curtain behind the three occupants covering the rear window. In the following shot from outside, behind, and above following the tow truck, there is no gray curtain in the back window, and you can clearly see occupants in the vehicle.
When Leo draws a handgun to shoot at the coyote that took Romeo (Suzie's dog), the handgun he picks up from the paint desk is clearly a P200-series Sig Sauer. When he shoots the gun, however, it is suddenly a 1911-style handgun, which he uses for the remainder of the film.
When Duke and Leo are in the van overnight Leo falls asleep with his glasses on. When he wakes up, the sunglasses are on the dash.
During the kidnapping of Suzie, the semiautomatic she tried to fire would not have clicked more than once. However, this is only true for a single-action gun; a semi-automatic will fire (click) every time the trigger is pulled.
When the coyote gets the little dog in its mouth, the stuffed dog takes its place.
In Duke's Manager's Office, the fire in the fireplace is obviously fake. It is a a flat screen TV playing a video of a fire .
Duke appears in a commercial on national television, something no one in the Witness Relocation Program would ever do.
Suzie said she couldn't find any history for Duke but if he were placed there by Witsec, they would've provided enough info to survive a background check.