Okay so you're driving to your parent's house and open up Google Maps for directions, are you going to start doubting its directions?
There is a difference between a joke being made by a person or a small company vs. implanting fake information in a source (Google Maps) which is taken prima facie by almost everyone in this day and age to be true and accurate.
Since you're on this site, I will assume for now (for sake of explaining my point) that you have a lot of knowledge on tech related stuff but perhaps have a blind spot in your medical knowledge. Suppose you have some illness and you go to research it at a popular and well-reputed site which claims to have information about medical illnesses. The site in the middle of nowhere has a joke about some random fact about the human body that someone without a medical science background could easily spot but you couldn't. You see now how this could suddenly fuck up your understanding of things and propagate down in your knowledgebase to then start affecting your decision framework? I'm tired and my example is a little far-fetched but I think you get the point I'm trying to make. Google can joke around come april time, but this kind of bull shit in "google maps" is not acceptable. My niece could easily take from this that human beings have the technology to pull off something like this in the way google is showing and make wild and inaccurate extrapolations that will confuse her.