Continuity: While on the subway looking at Finn's sketch book, the blood on Lustig's fingers changes in amount and placement throughout the scene.
Audio/visual unsynchronized: When Finn enters the Borough Club to see Estella, Walter is talking about Michaelangelo's artwork, but his lips aren't moving.
Revealing mistakes: During the beginning sequence where the young Finn is splashing through the shallow water, drawing in his notebook, you can see indentations in the page indicating where the creatures eye is to be drawn
Continuity: When Estella comes to Finn's hotel room to have him paint her, the soles of his feet are black. When Finn chases after her and gets into the taxi, his feet are clean.
Continuity: When Finn is yelling up at Estella's apartment after his show, his bottle of wine switches hands from the left to the right and then back to the left.
Continuity: The wallpaper on which Finn is drawing Estella's portrait was ripped from the wall, but when Estella enters the room we see the wallpaper intact.
Errors in geography: When Arthur Lustig visits Finn, Finn gives him his address as 111 Greenwhich St., which is south of the World Trade Center. The nearest subway stop is the Rector St. 1/9 train. Yet when Finn takes Arthur to the subway, they end up at the J/M/Z Chambers St. stop. When a subway train does come, miraculously it is the G train, which is the only train in the system that does not enter Manhattan at all. In addition, none of the above mentioned trains would take Arthur to JFK, his stated destination, without at least one transfer.
Factual errors: In the scene in which Lustig is shown on TV, the commentator mentions Lustig is due for death by lethal injection. Florida only began offering lethal injection relatively recently. When Finn was a boy, the method would have been the electric chair.