After the fight in the subway, the bruises on Eddie's knuckles appear and disappear between scenes.
When Eddie jumps off the cliff into the ocean, it is the middle of the day, but when he returns to the surface of the water, the sun is setting.
When Eddie talks to Vern, the stubble on his chin changes length between shots.
After Eddie cleans his apartment until it is spotless, he returns from a visit to his editor and walks into a messy apartment.
As Eddie watches Mrs. Atwood and her henchman with the injured cheek climb into the limousine, he wears a white shirt, then walks off in a striped shirt, then arrives and leaves the identity parade in a light blue shirt.
Eddie showed, in his hand, three keys, two of which were Schlage and the other was unrecognizable. None of those keys would have opened his apartment door, which he did some minutes later.
No, we don't access only ten or twenty percent of our brain, we access the totality of it.
There's no such thing as a "four-digit IQ". The maximum theoretical value of IQ is 200.
When Eddie talks to Melissa in the café, Melissa's response is instant to Eddie's line, the response is unnatural and partly cuts into Eddie's line.
If the pills made people as smart as depicted, there is no possible way that Bradley Cooper's character would "forget" to repay the loan shark.
In the cafeteria scene, when Eddie wants a loan of $100,000, he reveals that he quintupled his money four days in a row. Some scenes before, he started his investment with $800. Quintupled four times, that totals $204,800. So, why does he need to borrow money?
Eddie learned how to quintuple his money daily. He decides to borrow $100,000 from a loan shark to speed up the gains. He would have made $100,000 on his own in just over 24 hours if he kept quintupling his money daily.
Why did he need $100,000 so much that he would go to a loan shark? He never used the money as he got a high paying job after impressing a man at a party.
The utterances at the beginning don't match the utterances at 1:22:49.
Vernon mentions a known 'fact' that humans only use small percentage of their brain. While it is proven false a lot of time, it is still common enough misconception many people recite, so Vernon is probably doing the same without knowing much facts (it is implied he's not exactly using NZT himself, at least not often). Also of note is that misconception is indeed grounded in some scientific facts, such as that of approximately 90% of cells in the brain not being neurons, but glial cells known also as neuroglia. However neuroglia has its own uses in maintaining the neurons so humans are using it.