£2 Error Coin?

Nope.  There might be a slight bit of extra metal to the right of the mast, due to this being a very early-stage die crack. The late-stage die crack, a deteriorated die, resulted in extra metal that looked like a 'flag flying' on the mast.

That coin is erroneously referred to as an error. Errors are errors, such as coins being struck with the collar die missing, true hub-doubling, wrong-planchet strikes etc.  These are actual mint errors that mint employees are supposed to catch during the quality control inspection.

Early and later die cracks that show on coins create what are correctly known as varieties...not errors. However, the word 'error' connotes some sort of special status that translates into extra value and for this reason it is misused, often intentionally.  True errors are quite rare and sell for large premiums. Varieties can vary in scarcity. In this case, the 'flying flag' variety is the one collectors perceive as the valuable 'error' while this one might have some extra value over a regular strike to a specialist collector and no one else will care.