I just flew back to YYZ on 826 with this insane departure time. Be aware that the departure will, almost certainly, be delayed. My flight left at 0320 (and arrived on time) and colleagues who have flown recently also report delays.

The reason is that YYZ has a curfew between 0100 an 0530 or so. Since there is almost always a tailwind flying west to east, 826 usually runs ahead of schedule. Since they can't land due to the curfew, they have to delay the departure.