Harry gets a craving for blood, buys steaks and drinks the fluid then blends the meat for more fluid. Afterwards he can write again. However the red fluid in the meat is not blood but myoglobin, completely different stuff.
A mistake many people make.
During an argument Doris starts mashing random keys on Harry's laptop. When she leaves he begins typing again without deleting any text her action would have added to his script.
When Doris takes the pages from the printer, they are leaning against the top cover. On this model this should be the input tray, while printed pages would come out at the front.
When Harry goes to ask Austin about the content of the pills, he unloads the split-action shotgun and shells are heard dropping out. When he is seen reloading it, both rounds have primers that have already been hit with a firing pin.