Some sort of sanction is always theoretically possible but would seem unlikely, at least if you already are on your way out. However, I think the question and earlier answer miss the main issue, which has been alluded to in several comments.
If you present yourself to a Schengen external border on the day your visa expires, you should be asked how you plan to exit the area in time not to violate the conditions of that visa. The details of your visa are also much more likely to be scrutinised when entering than when leaving. And since you are clearly planning to overstay, it seems to me that the only legal decision is to refuse entry. Unlike possible sanctions for a brief overstay, this is not a matter at the discretion of the border guards, you plainly do not fulfil the conditions for entry as laid out in the Schengen Borders code.
If the border guards do notice and act on it, it would have severe consequences. You would be detained until you can be put on a plane back to where you came from. In addition to ruining this trip, it would create a black mark on your record that you will have to report for many future visa applications, even beyond the Schengen area.
If the flight you mention in your question is indeed a flight from a place outside the Schengen area then I would strongly recommend finding a ticket allowing you to catch an earlier bus or cancelling this trip altogether, even if it’s expensive.
Credit:stackoverflow.com‘