Errors & Omissions: Friends, Romans and fans of classical allusions...

Cross that bridge: James Lawton last Saturday wrote of "Andy Murray's latest failure to cross the Rubicon of great achievement". It was an attempt to raise an indifferent game of tennis (itself an indifferent game, but we won't go into that) to the level of the heroic. But if you are going to make classical allusions, it is better to get them right.

I am grateful to Hugh Hollinghurst for pointing out that the Rubicon was not a particularly big river. Indeed, its precise location is now a matter of scholarly dispute, as the coastal plain of north Italy flooded several times after the decline of the Roman empire. As Mr Hollinghurst says, crossing it was not a "great achievement" for Julius Caesar. Its significance was that it was the boundary between Italy, the territory of the city of Rome, and the province of Cisalpine Gaul. In order to protect the republic from military coups, generals were not permitted to bring their legions into Italy proper, and Caesar's decision to do so started the civil war with the forces of Pompey and the Senate. Crossing the Rubicon therefore signifies a momentous decision, one which passes a point of no return. Or, as Caesar himself is supposed to have put it at the time and as any reader of Asterix knows, alea jacta est, the die is cast.

Cameron Copernicus: In her column last week, Christina Patterson wrote about the clashes between the Prime Minister and Harriet Harman, the acting leader of the Labour Party. "Rightfully restored as the sun around which entire solar systems revolve, Cameron is confident, courteous, and funny," she said. It was strange to refer to solar systems in the plural: only one system can revolve around one sun. And Cameron may be confident and all, but it was odd to describe him as being "restored" to the centre of things, when this is the first time that he has been Prime Minister. Perhaps she was referring to his apparent sense of entitlement, or to his party's assumption, which Harold Wilson long ago sought to contradict, that it was the natural party of government.

Swap shop: Not only did yesterday's report of the American-Russian spy exchange use a clanging cliché, saying that spies facing years in jail "came in from the cold", but it also described Vladimir Putin as the Russian President. I do not know much about Russia, but almost the only notable thing that happened in Moscow politics recently was that Mr Putin took part in a swap of his own, changing jobs with Dmitry Medvedev, his Prime Minister.

Unnecess Abbrev: I hesitate to enter the heavily fortified barracks of military language, a subject on which Guy Keleny, the usual author of this column, is knowledgeable. But I thought Mary Dejevsky's item about British Army bloggers on Tuesday failed the test of common sense. She cited a blog by "Captain Sush Ramakrishna, the 3 Medical Regiment (3 Med Regt) Medical Officer attached to D Company, 40 Commando, Royal Marines". Did we really need the shortened name in brackets?

Name of the game: On Monday, Guy Adams reported that a new oil-skimming ship "could indeed be a game-changer" in efforts to clean up the Deepwater Horizon spill. The pollution of the Gulf of Mexico is not a game. The phrase ought to be confined to sports reports, as it was on Wednesday, when we reported that Andrés Iniesta "could be a game-changer". And Spain went on to win.

Hey, ho: I thought the Editor had banned the use of "hey". But it appeared yesterday in Simon Usborne's rather good sidebar – an add-on article expanding on some aspect of the main story, in this case a short description of how he had lost a game of chess to Magnus Carlsen, the 19-year-old Norwegian grandmaster who is now a fashion model. "But, hey, I suppose he is quite handsome, no?" Definitely not.