Continuity mistake: The train is stopped because Spectre has pushed a 1950's style Dodge truck full of flowers in the trains path. Later, when James is driving it trying to avoid the grenades dropped from a helicopter, the truck has turned into a very different looking 1961 Chevrolet truck.
Visible crew/equipment: When James Bond shoots down the helicopter then it crashes, he emerges from the rocks to run from the crash site to the right of picture, just as you see Sean Connery emerge from behind rocks from the right in the same scene. So for about a second there are two James Bonds in picture. One is the stunt man and the other is Sean Connery.
Continuity mistake: Just after Grant has hit 007 on the back of his head and knocked him out, Grant searches through the pockets of 007, he takes out some money and puts it into his lower left side pocket. But when 007 kills Grant and searches his pockets, 007 takes back the money from Grant's inside top right hand pocket.