From Combine OverWiki, the original Half-Life wiki and Portal wiki
- ...that the actor voicing the G-Man in the Italian version of Half-Life 2 is the actor voicing the Cigarette-Smoking Man in the Italian version of the TV series The X-Files?
- ...that the Black Mesa East and Kleiner's Lab teleports use the Calabi–Yau manifold?
- ...that the sequel to Portal originally didn't include portals and was actually a prequel titled F-STOP?
- ...that the Borealis is based on United States Coast Guard Cutters homeported in Seattle?
- ...that Judith Mossman was originally blonde and named Elena Mossman?
- ...that Gordon Freeman was originally named Dyson Poincare?
- ...that the Overwatch Nexus design was inspired by the Parliament of Serbia in Belgrad?
- ...that Gina Cross and Colette Green's HEV Suits were originally to be orange?