The ball bearings would not have stayed in the skull of the body under the influence of an MRI. While the intense magnetic field would have indeed caused the body to act as depicted, the bearings would have been ripped out extremely quickly.
When Marsha confronts the group, the sound of a shotgun being pumped is heard, despite her shotgun being a break-action model with no pump.
When the dead body is isolated in a room and the top part of the body is slammed up against the machine; supposedly because of the magnets, Booth draws his gun. There is no threat in the room. Possibly just for effect as his gun was slammed against the machine.
This episode implies that Roswell, New Mexico is a short drive, perhaps even within walking distance, from Juarez, Mexico. At one point, a character mentions that they see a glow over the horizon and somebody says the glow is coming from Mexico. In a direct line, Roswell is close to 150 miles from Juarez. The most direct driving route between the two towns is 208 miles and takes over 5 hours.