If that was a flight number it would either be AA or UA at the beginning, for American or United. Just like all Delta flights start with DL.
So, it's not a flight number.
If it was an aircraft registration number, the first letter or letters, Q or Q3 in this instance, would be a "country code".
For example, all US registered aircraft numbers start with "N" because N signifies US registry. Like N20808 which is a nice BT-13.
There is no "Q" or "Q3" as an International registry code.
Check this page for registry letters:
http://www.skytamer.com/iam/iam1.htm Once again, it's a hoax. Somebody was playing around in Word and pretending to be Nostradamus or something.