Do either of your friends have a drug history? When detoxing, you body releases old stored up toxins and that includes undigested/processed drugs that were consumed in the past. We are cleaning out more than just bad food but also everything you ate that the body didn't totally assimilate or eliminate. On my first fast two years ago I had a flashback and taste sensation from a major surgery I had undertaken 5 years prior. The effect lasted 2 days.
If your friends have taken anything like LSD or other hallucinagenics then they could possilbly be released back into the blood stream and go to the brain. If you weren't expecting that it would be a very distressing situation.
Remember that things sting twice! Once going in and once going back out.