When Picard speaks with the people from the addicted planet the signal is fuzzy, which is bad enough. However, when their leader ends communication, the Enterprise's view of the planet while it's in orbit is also fuzzy.
Yar is down in the cargo bay (waving - see Notes) when Crusher and Picard leave, and looks like she isn't going anywhere. However, when Crusher and Picard get to the bridge, Yar's already there.
Wesley: Data, I can understand how this would happen to the Ornarans. What I can't understand is why anyone would voluntarily become dependent on a chemical substance.
Data: Drug addiction is a recurring theme in many cultures. However--neither being human nor having had any comparable experience, firsthand or otherwise--I am afraid I cannot give precisely the answer you seem to hope for.
Tasha: I believe I can, Wesley. First of all, nobody ever wants to become dependent; that happens later.
Wesley: Still, if people know it happens, why do they start?
Tasha: Remember what I told you about life on my home planet? There was so much poverty and violence that, for some, the only escape was through drugs.
Wesley: Escape? How does a chemical substance provide an escape?
Tasha: It can't really. But it makes you think it is. It's difficult to explain, but drugs can make you feel...good. They put you on top of the world; you're happy, you feel in control of everything and everybody.
Wesley: But what's the point, if you know it's artificial?
Tasha: Because it doesn't feel artificial until the drug wears off. Then you feel just the opposite of what you did before: sad, powerless, hopeless, in pain...And the worst part is, the more often you take the drug, the more your body adapts to it--so that you need higher and higher doses to get back the good feeling. However, those larger doses also leave you feeling worse--and for longer--after it wears off. That's how you get trapped. Before you know it, you're not even taking the drug to feel good anymore; you're just taking it to keep from feeling bad. At that point, all you care about is getting your next dose. Nothing and nobody else matters.
Wesley: I see how it works, Tasha, but I'm afraid I still don't understand it. Sorry.
Tasha: Wesley, don't be. In fact, let's hope for your sake you never do.
Picard: Beverly, the Prime Directive is not just a set of rules; it is a philosophy, and a very correct one. History's proved, again and again, that whenever mankind interferes with a less developed civilization, no matter how well-intentioned that interference may be, the results are disastrous.
Denise Crosby wanted out of her contract so they wrote "Skin Of Evil" to get rid of her character. Then she received word of this episode (what the storyline was going to be) and she asked if she could remain for this one episode. This explains why they flip-flopped these two episodes.
During the filming of this episode, Merrit Butrick had AIDS and this was one of his final acting jobs before he died.
Judson Scott previously played Joachim is Star Trek II - The Wrath Of Khan.
This episode, filmed after "Skin Of Evil," was Denise Crosby's last playing the "real" Lieutenant Yar. If you look closely near the end of the episode, you can see Denise Crosby waving to the camera as Captain Picard and Dr. Crusher leave the cargo bay. Crosby would later return to play Sela and alternate-reality versions of Yar in time-travel stories.
Merrit Butrick previously played Captain Kirk's son David in Star Trek II - The Wrath Of Khan and Star Trek III - The Search For Spock.