An Australian physicist noticed an error in the OED's definition of the word 'siphon' (story here). The definition reads: "A pipe or tube of glass, metal, or other material, bent so that one leg is longer than the other, and used for drawing off liquids by means of atmospheric pressure". 'Atmospheric pressure' should read 'gravity', apparently.
There is nothing earth-shatteringly newsworthy about this story. There are lots of "mistakes" in the OED -- in definitions and spellings. That is because the OED is such a monolithic publication that it takes years to respond to changes. I once wrote to the OED to tell them that their definition for a particular creature (I can't remember which one now, possibly salamander) called it a reptile, whereas it had been officially reclassified as an amphibian. The reply said that that entry had been last edited in 1904! The definition of 'hare' calls it a rodent. At the time the Dictionary entry was written hares were defined as rodents, but they have since been reclassified. The updated classification is reflected in the definition of rabbit -- it is now called a mammal -- but only since March 2010, when the Rs were edited. The definition of hare will eventually be corrected, but it will take a while.
The OED is not the best place to check the current spelling of a word; it just can't keep up with the speed of change. It has 'take-away' hyphenated, for instance, even though more modern dictionaries (including its sister publication the ODE, or Oxford Dictionary of English) have 'takeaway' as all one word. The OED is not designed to be an everyday dictionary for checking spellings and current meanings. It is a historical dictionary, telling you when a word entered the language and when new senses of the word became apparent, or when a word changed in meaning.