"I see a car inside."
Translation:Bent látok egy autót.
What are the rules for word order? Is "Látok egy autót bent" incorrect? or "Látok bent egy autót"?
Both are correct.
The general rule is that the emphasised word/phrase is directly before the verb, and the verb itself is emphasised if it's in the beginning. Since in this case all of the possible sentences would be translated into English the exact same way, they are all correct and should be accepted.
One other rule is that if a word refers strictly to another one, you can't separate them, like "egy" from "autó" here. This might seem obvious, but in questions, for example, this rule means that the question word will always be unseparable from the word it refers to (most of the time the verb).