In the 1960 adaptation of H.G. Wells' The Time Machine an interesting question is posed at the end which was not in the original book, but it greatly added to the story. Per the actual screenplay by David Duncan it goes like this; 
After discovering that George had returned to the time he came from, 23 November, 802,701, Filby and Mrs. Watchett come into the parlor. 
FILBY: "But it isn't like George. - To return empty handed. To try to rebuild a civilization without a plan." (to Mrs. Watchett) "He must have taken something with him." 
MRS. WATCHETT: "Nothing." She looks around and discovers three empty spaces on the tightly packed book shelves. She walks to them. 
MRS. WATCHETT: "Nothing except three books."
FILBY: "Which three books?" 
MRS. WATCHETT: "I don't know. -- Is it important?" 
FILBY: (smiles) "No, I suppose not. - Only...what three books would you have taken?" 
Answer the question, which three books would you have taken to the year 802,701 where all books had decayed to dust? Which three books?