The license plate of Clas Greve's car is a Dutch diplomatic plate. The letters "CD" (for Corps Diplomatique) on it are issued exclusively for that purpose. But he is not a diplomat and no diplomat may lend him such car.
(at around 25 mins) When Roger Brown is researching Clas on the Internet he sees an article "Terrorist Cell hunted down by TRACK" which says "...three men was killed."
(at around 41 mins) After Roger Brown has pulled Ove from the lake and they both are in the car, driving to Ove's place, Ove is still dizzy and disoriented and keeps falling on Roger's shoulder. At one point, Roger pushes him away, Ove pukes a little, and then you see a hand pat Ove on the shoulder. That hand came from back seat, and doesn't belong to either Roger or Ove.
(at around 1h 30 mins) The empty bullet casings in the final shootout are much too large to have come from either gun fired. They appear to be rifle shells.
(at around 1h 11 mins) When Roger Brown returns to Oslo after the car crash he is seen calling from a pay phone in Grønland Bussterminal, in the next shot he is seen walking over a bridge towards the bus station.