Alright, So I recently talked with Harry Teasley (One of Half-Life's Level and Model Designers) and he provided some Info about the Game's Design based on his Recollection.
. Harry had worked on the Apprehension Chapter while also worked on most of the Other Levels along with Several Textures.
. The Photo of His Daughter (Isabel) was Originally in a Destroyed Office on the Surface (Most Likely in Surface Tension).
. Chuck Jones had done the Wide Eyed MP (Military Police) -
https://combineoverwiki.net/wiki/File:MP_barney.jpg and Ted Backman Versions of Barney. -
https://combineoverwiki.net/wiki/File:Bm23.2.png. It's known that there's a Photo of Apprehension that shows a Room in c2a3a that Isn't connected to the rest of the Map. -
https://combineoverwiki.net/wiki/File:C2a3a0000.jpg According to Harry, He told me This Room was just a visual Idea and he recalled that "there were many simple constructions done like that."
. Harry also Worked on the First Version of the Crowbar along with interations of Gordon and the Zombies. (An Early Crowbar is in the Half-Life SDK as crowbar.max and it was reportedly discovered back in 2015 -
https://web.archive.org/web/20160628145442/https://facepunch.com/showthread.php?t=1253345&page=92 [Scroll down to Post #3674 dated 28th July 2015 by DoktorAkcel] and was said to lack bones but had vertex animations suggesting the Model was made Very Early when Half-Life's Engine was more Similar to Quake in terms of Model Handling] )
. Now while it was stated The Female Scienist (Which would've appeared in the "Communications Center" Chapter that became "Forget About Freeman") was cut due to Valve thinking the Technology was unable to handle the planned scene (Although other places say it was due to lack of texture Memory) Harry recalls the Model was probably cut due to Valve thinking the model probably wasn't Good enough.
. Harry Recalls the Xena Pinup Posters (Seen in halflife.wad) were in Gordon's and Other Scientist's Lockers plus other Parts of the Game but they were replaced with Generic Posters "due to IP Issues having those in the game."
While this info probably may not be Much, it Does give an Insight as to what work some of the other developers had done (Such as Chuck Jones working on Barney) and also Sheds Light on the Mysterious Apprehension Room seen in that 1 Particular Screenshot (Along with also being seen in a Worldcraft Editor Shot) and possibly other bits that may be interesting.