"The elephant plays around midnight."
Translation:Elefanten leger omkring midnat.
That would be "ved midnat"
"ved midnat" would mean "at midnight", not "around midnight"
You can't use "om" with midnat because "om" denotes something happening within/during a time span. That doesn't make much sense for midnight which is only a single point in time. You can say "om eftermiddagen", "om natten", "om efteråret", "om mandagen" and so on because those are periods of time.
This is from a book titled "Danish: An Essential Grammar": When used in association with time, Om is used to indicate a FUTURE time. Example: De rejser om en time (They are leaving in an hour).
Since this sentence seems to imply a meaning of "Elephants play sometime around midnight" so omkring (around, about) is the better choice. I think... If I am wrong, someone please step in and correct me on this. Mange tak!