Did you know?

In Half-Life 2, Dr. Breen implies that Gordon had been working for a short time, but the Episodes describe various stories involving him and Barney that would not be realistic for a short tenure. This likely suggests May 16th is not the date, as the date of his employment is implied to not be changed.
Several entries from Adrian Shephard's diary are given in the Opposing Force instruction manual, written by Gearbox writers. March is used, corroborating the Raising the Bar date. Shephard says in his last diary entry, written on March 15, "We were told today to be ready in case it happens tomorrow.", suggesting that the incident occurs on March 16. It seems that the Gearbox writers replaced May by March: in the Half-Life instruction manual, Freeman is said to start working at Black Mesa on May 15, he is also said in the Half-Life PlayStation 2 instruction manual to attend the Hazard Course on May 16 at 7:30 (in a Hazard Course schedule with dates all set in May), and Barney is said to start his duty on May 16 at 9:00. Therefore May 16 was the best day for the incident pre-retcon (see above point), and consequently March from Shephard's diary would have been replaced by May, for consistency of the original timeline.