Depending on the context: zlý (evil, wicked), zlobivý (e.g., a child), neslušný (bad behaviour) and many less common synonyms.
So often people complain that something is impossible when it would be enough to employ their phantasy just for a short time. Someone can cut a wrong tree (he was meant to cut a different one). You could get a wrong tree (ordered a different kind). The options are countless...
I think for most people, they don't understand it account that Duolingo is using these words and phrases to teach the basics.
Easy. You ask your gardener to plant a pine tree. He accidentally plants a cedar tree. You say "that's the wrong tree!"
I, as a Polish speaker though špatný meant "ugly", because that's what szpetny means in Polish.
Android shows this as "wrong tree", should this be more like "bad tree" as in rotten?
For example, in the good film "Terminator", the first Sarah Connor is the wrong person, and for example in our history, Hitler, him, is a bad person. I suppose "špatný" means "bad" or "wrong": question. Voila, sorry for my english ^^.