David has only been in the US for a few weeks when he calls his obviously pregnant wife, Angie at home in England. She was not noticeably pregnant before he left, nor was it known that she is pregnant.
When David and Ron are in the car after leaving Ron's mom's house, the backgrounds seen from the moving station wagon are unrealistic, including a car seen being passed while Ron makes a right hand turn, but when the cut returns to Ron, he is driving straight.
There is a scene where Bowie opens a car window to have a cigarette and this causes all of Oberman's important papers to fly out onto the road. However, when Oberman pulls the car over (to collect all the papers from the road) you can clearly see that the only window in the car that wasn't open was the one that Bowie opened and then quickly closed.
Ron's station wagon has no rear license plate, which is mandatory in every US state. It also has no front one, then later it has a back plate.
Ron pays at a bar with a $20 bill that was designed in the 21st century.
Johnny Flynn was much too old to be playing a young Bowie. Flynn has obvious 'crow's feet' and a man of 24 would not, among other things.