(at around 3 mins) As everyone is talking around the table and the camera angle changes back and forth the position of the olives changes back and forth from inside to outside the rim of the glass, and the level of Bloody Mary mix changes in Fiona's drink.
When Fiona plants the explosive block under the car and detonates it, the explosion should originate from under the car; however the explosion comes from inside the car and only seems to have enough force to blow out the windows and start a raging fire. A full brick of C4 would have enough explosive force to lift the car and seriously deform the car's shell.