Counts as a Stealth Pun, too: While all the other original Half-Life titles were about things coming apart, Blue Shift was about things coming together. In astronomy, guess what being blue-shifted means?
Freeman is a theoretical physicist by training and has a Ph.D., but even when he still had a job at a research firm the closest thing to his actual qualifications he did was shove a cart around. The answer? His age. He's only 27, meaning he only got his Ph.D. a couple years ago at most. Hence his job title is "Research Associate", which is probably a pretty low rung on the corporate ladder.
It's also implied that there's a rotation for test chamber duty, and that day just happened to be Gordon's turn. "Looks like you're in the barrel today." Perhaps the G-Man even made sure that Gordon was the one in the suit on the day of the fateful experiment.
Ever wonder why the HECU soldiers act so tactically inept in combat? The training section of Opposing Force gives the answer. You (as Adrian Shepherd) are promoted from "Maggot" to "Soldier" in no less than a day, and then immediately assigned to duty. Real soldiers would need months, or even years to prepare for such a large-scale incident like Black Mesa.
Given the Shared Universe, the lore details thrown out in Portal 2 and Counter-Strike: Condition Zero retroactively add more context to the U.S. government's behavior in the first game. In Portal 2, Cave Johnson is allowed to conduct grievously unsafe and immoral experiments that result in many deaths without setting off too many alarms, even when they result in his own death. In Condition Zero: Deleted Scenes, global terrorism is depicted as a much more decentralizednote The largest group in the world, stated to be Guerrilla Warfare, has 2,000 members. and dangerous threat than in the contemporary real world. Most notably, two missions feature terrorists seizing nuclear missiles in the ex-USSR, but there are other signs such as relatively small groups racking up huge death tolls (e.g. the Elite Crew, with "several hundred members", killing over 3,000), Baltic terrorists deploying jet aircraft and main battle tanks, the apparent presence of a major insurgency in the United States,note The Midwest Militia, only one of the groups fought in U.S.-based maps in Condition Zero, is stated to have killed more than 1,000 government employees. and the sheer number of heavily armed militants your characters end up killing in what are in the real world quiet backwaters, such as 100+ terrorists based in a small town in rural Veneto, Italy. Together, these games paint a picture of a world that's both more unstable and more callous than in the real world, explaining both the U.S. military's scorched earth attitude at Black Mesaand said government contractor's complete lack of safety standards.
Some have questioned why the Hazard Course, ostensibly designed to help scientists acclimatise to the HEV suit, features firearms training when in reality they'd have no need for it, and indeed why what is essentially a beefed up hazmat suit has "munition level monitoring" and a "defensive weapon selection system". But remember that Sector C isn't the only place where the HEV is used, where else do you see HEV suits? That's right, Xen. The HEV seems designed first and foremost to be used for the Xen survey expeditions (note how many dead HEV suit users you see in Xen compared to the three HE Vs that seem allocated to the anomalous materials lab. These scientists would of course be carrying weapons to defend themselves against the hostile Xenian fauna and so being able to quickly see how much ammunition they have and what weapons they have available would be quite useful for them. The firearms section in the hazard course could be explained as a way for the higher-ups to see who is particularly skilled with firearms, so they have potential candidates for Xen survey teams.
What if a Resonance Cascade scenario actually has different levels of severity? What if the one in game was a low level one or a mid level one? What the hell would the worst kind be like?! A universe collapsing into the Big Crunch?
The surviving scientists at the Lambda Core's plan were to teleport Gordon into Xen so he could destroy the mastermind behind the invasion. But they never even mentioned how they were going to bring Gordon back to Earth. It's entirely possible that the scientists at the Lambda Core were planning to just sacrifice Gordon for the sake of humanity and to leave him there, stranded in Xen for the rest of his life if the G-Man weren't to intervene.
The fate of the scientist and guard from the "Xen Portal" scene, Gordon manages to escape into the portal once it's opened but what did the two of them do since they would then have no one to protect them from the Xen masters swarming the area.
Many people have noted that the Gonarch looks like a spider monster with a giant testicle (which Word of God confirms is intentional), now keep that in mind and consider that it's main attack involves dousing you with a harmful white fluid.