Concur, 5meo typtamines are extremely potent and quite dangerous. Witnessed overdoses and while they weren't lethal, they certainly had the risk. Just because the compound doesn't kill, doesn't mean you can't die from a secondary or tertiary effect.
To maximize safety:
1 - don't eat or drink for at least 4 or 5 hours beforehand, so there's nothing in your stomach to vomit
2 - lie in the recovery position ( https://en.wikipedia.org/wiki/Recovery_position ) with one's mouth facing downwards to minimize the chance of aspirating any liquid
3 - don't move around
4 - be with a trained, trusted, and experienced practitioner, who you've vetted thoroughly and who you are sure can keep you safe
5 - again, don't mix substances!
Great episode, but that scene is pretty disturbing.