In the scene where the two Amitabh twins meet, the actor playing Amitabh's twin seems to be wearing a black/white check shirt, while Amitabh (when playing the same character) is clearly wearing a black/white wave pattern.
The casino booklet that Vijay receives has the instruction to go to the toilet, but there is a spelling and grammar error. The instructions says, "Go to sixth floor toilette".
When Jay jumps on the roof of the train, clearly on screen right there is the camera man sitting on the grass filming with his 35mm camera, clear as day and you immediately cut to the footage that he is filming, such a Lame, lazy way to film,all they needed was some sort of camouflage to hide the camera.
The car that Jai and Mala use has a registration based in the Netherlands (with the short-hand NL) although they are based in Venice/Italy. In this scene however, it is shown that they were in the Netherlands.
Jai and Mala are shown in an airport in Italy (Jai was using a telephone booth with Italian text), however when both come out, they are shown to be driving a car with vehicle registration from the Netherlands (denoted with NL), which shows that they were in the Netherlands.