It was unimportant; in the subs the waiter asked if she wanted tea, in the dubs it was if she wanted coffee after her meal.
IIRC it was the DVD release of Tenchi Forever.
This sort of difference is one of the reasons I will always prefer subs.
I guess I could be the odd one out but I'm not keen on the 'localisation' efforts that replace the cultural elements of the underlying media, e.g. how in Ace Attorney ramen is replaced with t-bone steaks (iirc?), prompting the meme 'Eat your hamburgers, Apollo'
P.S. For an example of when "yes" might really mean "no", I heard an anecdote. An American guy had been hired by a Japanese company to work in their offices in Japan and be a liaison to foreign businessmen. He was attending a meeting once where everyone but him was Japanese. The boss presented an idea. There was silence for about 10-15 seconds, then people said things like "Yes, that's a good idea, let's do that." The American left the meeting thinking that the idea had been approved, only to have his Japanese colleague explain to him that the key part was the silence. The boss clearly heard and understood the message that his employees didn't think it was a good idea, and the idea was dropped and never mentioned again.
So I could see a case where the character says "Yes" but the subtext is "No", and that would be clearly understood by a Japanese viewer. Different translators would choose different approaches there; some might translate the text, and some might translate the subtext. I'm curious to know if this was a case like that, or if it was a clear-cut case of one translation being right and the other one being flat-out wrong.