"– Hi! What is going on? – Well, nothing special."
Translation:– Hei! Mitä kuuluu? – No ei mitään.
They have actually different meanings. Let me explain.
Ei se mitään means something like "that's ok" or "no worries". It's usually used when something undesirable has happened and someone shrugs it off or acknowledges it's not too big a deal. You can think it like ei se [haittaa] mitään, along the lines of "that does not hinder us (too much)".
Ei mitään means literally "nothing". In this exercise more accurate translation for "nothing special" would be ei mitään erikoista or ei mitään erityistä as noted in other comments.
Edited 2021-02-09: fixed typos, added hej and moro, added clarifications
The short answer
Probably the word moi has not been keyed in. Please report and let us see if it gets accepted.
The long answer
Which greeting to use is one of the trickiest things in the social interaction Finland. It all depends on how well you know the persons to be greeted, is this a business/work, service or free-time situation, how old they are, how old you are and so on. Here I present the most common greetings for non-formal greetings that are not bound to the time of daynight (vuorokausi). Note, these are for when you meet someone, not for departing.
- the most formal of these here
- always useable, but according to a discussion I found on the page for Institute for the Languages in Finland (Kotus) preferred by men in general and by women when addressing men
- used by some when terve feels too formal
- preferred by women when addressing women
- the Swedish-speakers' variant of hei
- depending on the speaker this may sound exact as the Finnish version or something different
- the most informal of these here
- mostly used in the southern parts of the country and by young speakers
- according to the discussion I mentioned above, some require high level of acquaintance, i.e. not to be used when addressing strangers
- used in the Tampere region (the province of Pirkanmaa)
- sometimes perceived as highly irritating by others
The easiest way is to follow the suite, i.e. use the same greeting that you were greeted with. If you need to greet first, terve is the safest bet.
Yes, I did report it.
So, I from my experience in 3 years living in Helsinki, moi is by large the most common greeting. Hei is very rare (for hello, but hei hei is common for goodbye, although moi moi Is more common). I've heard hej (Swedish) more than hei in HEL. Terve is more formal, yes, I see it. I've heard it more in businesses. Now, I'd say say moro is more common than hei. And sounds very informal to me. I now live in Tampere, but very little interaction under Corona, so I haven't observed enough. Yet. Kiitoksia!
Can you specify what part you find confusing? Mitä kuuluu? is extremely useful phrase when meeting someone you already know, like "how do you do" but less formal. No ei mitään is also useful as an answer when you have nothing special to tell – either nothing has happened or you are not willing to tell.
What is going on? –doesn't it mean the same as "what's happening?" which would be "mitä tapahtuu?" in Finnish? There are many ways to translate "Mitä kuuluu?" but I don't think "What's going on?" is one of them.
Nothing special. – should be Ei mitään erikoista/ihmeellistä/kummempaa. "Ei mitään" is just "Nothing." I don't think I've ever heard someone answer like that to "Mitä kuuluu?"
Are you asking about the comma? If so, you are absolutely right: there definitely should be one. A very good catch. The word no is an interjection ,exclamation word, which should be separated by a comma. But to my knowledge Duolingo does not care about punctuation at all on any course with one exception: Klingon. (The reason being that Duolingo does not support the real Klingon alphabet, so "Federation standard" alphabet must be used.)
Probably it was not accepted because it is Miten menee?, How is it going? or What's up? (I can hear the voice of Väiski Vemmelsääri, Bugs Bunny in my ears).
There are a lot of informal greetings both in Finnish and English, and "to pair" them is not a trivial task.
- Mitä kuuluu?
- Miten menee?
- Kuis pyyhkii?
My advice to a language learner is to stick with the most standard one, Mitä kuuluu?, i.e. use it. With time you will learn the others.