Plot hole: At the beginning of the film Lustig suddenly emerges from the water right in front of Finn. It's not possible that he could have been hiding in the shallow water without Finn noticing him. (00:03:40)
Plot hole: How on earth did Lustig's killer get on the subway, when the three guys who were after him couldn't? (01:34:00)
Plot hole: Before Lustig dies he gives back Finn's scrapbook that got lost during their first encounter. In that scene there is no evidence that Lustig gets hold of the book, and the only explanation would be that Lustig picked up the stranded scrapbook later. This looks quite far-fetched to me, especially since Lustig was hiding in the dunes, and the scrapbook looked way to good to have spent a long time in the water. (01:35:20)
