Factual error: Bilbao is in the Basque Country, which has its own police force, the Ertzaintza, that is independent from the Spanish National Police. When the police burst into the Swiss banker's flat, it is the Ertzaintza who enters, with their traditional red caps. However, when Bond is walking away, the police cars that are going towards the crime scene belong to the Spanish National Police, which has no jurisdiction in the Basque Country.
Audio problem: When Bond arrives at the King Industries place where he meets Elektra King, watch the man he talks to when he gets out of his car. It is painfully obvious that the man's mouth is not in sync with what he is saying. Even worse, the voice is not even his. It is slightly higher-pitched than the man's real voice when he finally talks right.
Factual error: In the final battle, Bond shoots up the dive controls of the submarine and it dives vertically down, straight into the bottom of the Bosporus. The sub is said to be a Victor-III that is about 100 meters long. The Bosporus around Istanbul, however, is only about 50 meters deep, so the rest of the sub would have stuck out of the water, not be fully submerged as shown.
Plot hole: In the Banker's Office, Bond takes the strap from one of the window blinds to facilitate his escape. Overlooking the large quantity of cable he ties round the belt of the villain and his own belt, there must be an awful lot of strap for one blind to allow him to drop from that high up to the ground (well over 50ft?).
Revealing mistake: During the gun battle after Renard escapes the bunker, someone gets shot, and you see the stunt bloke dive to the floor and scream even though the gun wasn't even pointed at him or any bullets fired. He's the one standing just to the right of the jeep as we look at it.