By trying to make testing the driving on a full bladder myth safer and replicable Adam and Jamie actually invalidated the results and made it more dangerous.
In real life people's bladders tell them when they need to pee, they don't wait till an ultrasound says their bladder is full. People also don't usually wait till the point of physical pain to start their journey, and would have just pulled over and found a bush if they were that desperate.
Adam says that drinking too much water is a risk (a burst bladder is the only risk in these circumstances), so to avoid that he drank far more than he wanted to and literally filled his bladder to bursting point, something he never would have done by himself. People in desperate need of a toilet don't keep drinking.
The build team said the superglue seatbelt myth was busted because it only works if the person has a metal skeleton, with a metal plate attached, bonded by superglue to another plate. However, even with all that Buster was still very, very dead.
Every part of Buster not glued to the seat was subjected to the full force of the crash, detaching them from the torso and his head ended up down his back.