Goodbye Mrs. Slocombe - S10-E1
Other mistake: When Mr. Humphries first comes back to the department in drag and talks to Capt. Peacock before being directed to the Ladies Dept., you can see, in the background, Mr. Spooner trying desperately (and unsuccessfully) not to laugh.
Goodbye Mrs. Slocombe - S10-E1
Audio problem: At the end when Capt. Peacock comes onto the floor in his maintenance garb, Mr. Harman points him to a spot on the floor and tells him to mop it up. In the initial shot Harman is indeed telling him, but when the camera cuts to another angle Harman is visible and still talking but his lips aren't moving.
Goodbye Mrs. Slocombe - S10-E1
Revealing mistake: At the end during the credits, Mr. Humphries and the Lady he played are onscreen at the same time and you can see the splice made to allow that to happen.
Answer: It usually just means seeing something weird or unusual, perhaps something someone wouldn't believe you saw without proof. The phrase is usually "haven't got your gun", although some people replace "gun" with "camera." Basically think about a hunter spending all week in the woods looking for the biggest [fill in the blank] and the one day he goes out into the woods without his gun and then finally sees it.
Bishop73