Does the calendar support events that span midnight?
Yes. It also supports multi-day events that have no times associated with them. For the purposes of this documentation an event "spanning midnight" would be an event with a start date, no end date, and an end time earlier than it's start time.
When looking at a day or week view if your scroll the times until you can see into the morning of the next day you'll see any events that start in the current day and span midnight into the next morning. And you'll see any events that start the next morning. But note that you won't be able to scroll very far into the next morning: the calendar will stop as soon as all the visible times would be in the next day.
Also note that when looking early in the morning of a day (so the earliest times read midnight, 1am, 2am, etc.) you won't see any events that began the day before. You'd need to look at the evening of the day before to see them.