Don't see anything alarming in what they did. I would just check with HR next week and see if the start date is still good. They'll let you know at that time whether anything came up on the drug test. Just don't mention the drug test.
I don't like these detox drinks. They're ver6y unreliable and mainly work by dillution. Which can work for some light smokers. But for heavy smokers they usually don't work.