Blue dragons' subtype is Earth, yet they have access to spells from the Air domain. (At least according to the SRD.) Should that be the Earth domain, or is the SRD in error?
Nothing is in error....who says that a subtype needs to dictate the domains the dragon has access to? Blue Dragons are dragons of the desert environment, which includes both earth (the sand) and air (the wind). And their spell-like abilities are the 'mirage' factor.