What are my sister’s rights if she recently purchased a car from a used lot and 5 minutes the front wheel fell off?

If she purchased the car "as is", she will need to fight hard and quickly to get the dealer to take back the motor vehicle and refund her money. As is means there is no warranty and she pretty much runs the risk of such things going wrong with the motor vehicle as soon as it leaves the lot. The good thing though is there is generally at least some sort of state required limited implied warranty for such car dealers but your sister will need to file a complaint with consumer protection agency in your state that handles such complaints. Start with the attorney general and also try the city attorney or county attorney. Then, there is such a thing as the unfair and deceptive practices act most states have for the benefit of consumers; it appears the dealer may have violated such state law in your state. Make sure come the end of the weekend, your sister begins the complaint process.

Unfortunately, it appears that your state's lemon law only applies to new cars, so that will not help her. That means that only if the dealership either knowingly mispresented (or lied), or knowingly omitted to reveal a fact which any reasonable seller would have, would they likely be liable. In other words, if your sister can show that they knew--or perhaps reasonably should have known--about the problems (which may well be the case), she may be able to either rescind the sale (return car, get money back) or keep the car but get monetary compensation. Note that she'd have to sue to get this, if the dealership will not voluntarily rescind or compensate.

If however the dealership truly was innocent of any knowledge that there was a problem, it will be harder to establish liability against them. And if any problem occured after driving off the lot (e.g. she hit a big pothole fast, which popped the wheel off), they are not responsible.

Overall, it seems like there is at least a reasonable chance she has a case, since is likely they knew or should have known of these problems, and hence could not sell the car without disclosing them. It would be worth her while to consult with an attorney, if the dealership will not voluntarily correct matters.