Factual error: Morris manages to rake up 5 million pounds in cash. Even if they all were £50 notes (which they aren't, there are at least 3 different denominations in the props), there still would be 100,000 of them, much more than what the little bag they empty in 3 handfuls could contain. (01:20:00)
Continuity mistake: Morris shows his client the ad he put in the newspaper, irritating him for the way he keeps bobbing his hand. Seen from Morris' perspective, he holds it with the pinky finger curled and sticking to the other side of the paper, which is not true in the reverse shots. (00:07:15)
Continuity mistake: Joe Lo Monaco is having breakfast with his lawyer, Morris. The banana in his hand is more chewed or less chewed between shots; for instance, after he tells Morris"I didn't fly you to LA to bake in the sun", he chews it till he reaches the peel, but the edible part stick out again in the next shot. Moreover, a new intact banana appears on the tray where he put the half-finished one before. (00:06:00)
Plot hole: The whole premise of the movie hinges on the fact that someone is going to try to buy the ship off James Coco for 3 millions, to try and sell it for 5 to Morris, who put a false ad on the newspaper but he's gonna hightail after. First; it's unclear how whoever checks out of the ad with the 5 million offer is going to be aware that Joe Lo Monaco has a ship for sale for 3 mil; he did not put an ad out himself, and who checks out of the morning paper looking for multimillionaire bargains on ocean liners? It's something entirely out of their league for the gang of small crooks shown in the movie and that Charleston ends up helping. Even more absurd is the fact that Morris plans to disappear after the 'sting', but he is running it with his own real name and in London, where he works as a high profile lawyer. Not the kind of person who can and would just 'disappear' into thin air, especially when the sting could have been done in any other part of the world.