Early on, during a gunfight in an alley after the market scene the windscreen of a car is shot and shown in pieces. Afterwards they get in the car to escape and the windscreen has returned, intact.
During the chase with the Chechens in St. Petersburg, the two cars, Palmer's and the Chechens, are shown rounding a corner. The Chechens' car has a smashed right headlight, then an intact right headlight in the next cut, and finally runs over some trash cans in the following cut, inflicting the damage seen two cuts prior.
Harry has to suddenly go to Beijing. But Britons need a visa, and he has no time to get one.
Harry's Aeroflot ticket from London to St. Petersburg would have been paid for in pounds, but shows a price conversion from pounds (GBP) to Canadian dollars (CAD).
The weapon is said to be biological, and requiring two parts to be active, i.e. a binary weapon. Only chemical weapons are binary. Biological weapons are either infectious or not.
When Harry is given a choice of weapon to obtain, he tells the dealer to give him the Colt. But when he gets into a shootout, he's using a Russian Nagant revolver, not a Colt.
In the end credits roll at the end, Special Effects is spelled "Special Effets".