Revealing mistake: When the team attends Han's funeral, Deckard Shaw is watching the team in a Maserati Ghibli with tinted windows. When Dom notices him he then chases Shaw in his muscle car. During the chase the Maserati Ghibli is seen twice with clear windows with a man in a mask behind the wheel. When Dom and Deckard come face to face with the cars and then crash into each other, the Maserati Ghibli is then seen again with clear windows. After the crash when Kurt Russel makes his entrance the crashed Maserati Ghibli still has clear windows.
Revealing mistake: When Dom is first chasing Shaw, we see him swerving between cars on a bridge. If you look very carefully you can see at least one of the cars is not actually moving. Pay attention to their wheels. The most noticeable instance is where Dom goes to the right of a dark coloured Mondeo. Slow-mo helps but is not essential to spot this.