The soy-diesel pickup truck in which Donna, Josh and Toby ride has a license plate on both the front and rear. In Indiana, license plates are displayed only on the rear of the vehicle.
During one of the job interviews for presidential secretary, Jed Bartlet mentions how Air Force One is flown by a general. Presidential pilots, 1944 to present, have the rank of either Colonel or Lieutenant Colonel and serve a number of years in this position regardless of who is in office.
When Bartlett addresses all of the service personnel at the military base, they would all be called to attention BEFORE he walks out on the stage and he would then tell them, "At Ease," or something to that effect.
While riding in the bed of a diesel-powered pickup truck in Indiana, a local man tells Josh that the glow plugs heat the fuel, and then the engine "just runs", as though the glow plugs act constantly and in all weather. However, that's not the function of the glow plugs; instead they, one for each cylinder, warm the combustion chambers and the incoming air, but only in cool or cold weather, so that the engine starts more quickly and more easily, and, as soon as the engine starts, they cease heating until the next start under circumstances requiring them. Of course, on modern engines the glow plugs are computer-controlled.
When Margaret tells Leo the president is on the phone, you can hear her flip-flops smacking as she walks. This is not the first time the show has neglected flip-flop sounds. (They are commonly worn for comfort by women on set when their feet are not going to be on camera.)
At the gas station where Donna, Josh and Toby wait for a ride after the truck runs out of diesel, there is a sign on the counter that reads "No credit cards - cash or checks only." The cash register displays logos for MasterCard and Visa, implying that those cards are in fact accepted.
When Josh, Toby, and Donna are in Indiana, all the cars and trucks they are in have Pennsylvania inspection and registration stickers on the windshield.
Cap keeps correcting everyone that the truck runs on diesel, not gas. However, he tells Toby that he can't make a truck run out of gas. He should have said diesel, not gas.