Regarding checking on Khan, I think it could easily be a left-hand not knowing what the right-hand did situation.
The U.S.S. Dunsel stopped by six years earlier, didn't find a planet where a planet was supposed to be, concluded they blew up and didn't bother to do a thorough checkout, and for whatever reason Reliant didn't have those records.
And I agree regarding Terrell's 'cargo containers' line being able to be taken different ways. He did say that they 'look like cargo containers' meaning it's possible he wasn't sure because he was unfamiliar with the design, or that they were just in a state or disrepair/disorder from the sandstorms and thus just not immediately recognizable. Or, he could have just been a bit surprised to find cargo containers in the middle of a sandstorm.
The U.S.S. Dunsel stopped by six years earlier, didn't find a planet where a planet was supposed to be, concluded they blew up and didn't bother to do a thorough checkout, and for whatever reason Reliant didn't have those records.
And I agree regarding Terrell's 'cargo containers' line being able to be taken different ways. He did say that they 'look like cargo containers' meaning it's possible he wasn't sure because he was unfamiliar with the design, or that they were just in a state or disrepair/disorder from the sandstorms and thus just not immediately recognizable. Or, he could have just been a bit surprised to find cargo containers in the middle of a sandstorm.

) where Harve Bennett specifically said they went back and looked at TMP cargo sleds to use them as a basis for the cargo containers in TWOK, besides, there are 'on the set' photos I've seen, that clearly show them to be full scale TMP style cargo containers. So I guess this means the TOS E must have used similar containers?