The exterior shots of the frozen yogurt shop, which are stock footage, show the front door opening outward. From the inside, the frozen yogurt set was constructed with the door opening inward.
Even if the yogurt were fat-free, it's high in calories and sugar, so consumers would still gain weight.
Jerry's suggestion that his doctor told him to entirely remove fat from his diet is an impossible one: many vitamins only solubilize in fat, making it an essential nutrient.
After Kramer and the scientist kiss and kick the rolling chair, it knocks the vial contents of the yogurt sample into the vial containing Giuliani's blood sample. Anyone would have seen the vials all messed up and immediately discarded the original samples.