Actually, aside from the missing tilde, it is
not incorrect, but grammatical and idiomatic. Some verbs in Spanish are used in the third person with the reflexive pronoun to express an impersonal statement, similar to the passive in English. Thus 'se habla español' is not intended to mean 'he speaks Spanish' but rather 'Spanish (is) spoken'.
http://www.123teachme.com/learn_spanish/passive_voice_2
(Incidentally, the character of Dr Nick is based on a member of the creative team behind the Simpsons, one who grew up in Mexico, so he conceivably does speak Spanish and we can attribute the missing tilde to an anglophone typesetter).