What can happen if a recommendation letter falsifies information? For applications of virtually any kind, it is stipulated that an offer may be rescinded or even during a course, a student may be taken off, if any false information is discovered in their application.

However, suppose for a graduate program a student asks a professor to write a recommendation, and whether knowingly or unknowingly the professor includes false information in that letter of recommendation which has a bearing on the application, what are the consequences of that?

The onus of selecting the recommender is on the student/applicant, but I do not see how they can suffer consequences since recommendation letters are often not shown to the applicant. 



To help answer the question, assume I am referring to universities in the U.S.
Few cases can happen (probability will decrease as we go from case to case).


(They don't find out) nothing happens.
(They find out) they'll remember the professor and his recommendations will be considered of no value 


The reader of this recommendation can have the professor marked as a dishonest person within the facility or keep it for himself

They contact the professor ask him about it. Then they contact the current professor's employer and he gets in 'trouble' - some people get aware of it.
They contact current professors employer, he get's fired for dishonest behavior
They make a lot of people aware (Including his colleagues and newspapers/media?) he gets fire and it's going to be hard for him to find another job, highly unlikely.


It really comes down to the credibility, you're not going to jail because of that. It can only really hurt your trustworthiness in the academic and human sense. If you're going to lie it should be something small like if someone worked in your company for a year you can say he worked there one and a half years. 

If the one recommending someone isn't aware of something chances of this affecting him are very low ~0. This is in the case of something that common sense dictates, he shouldn't be aware of I don't know, Like does he have a dog, and on the other side, one can't say he's was not aware of his e.g. effort or performance.