Hemingway claimed that he could leave out a lot of details as long as he knew what those details were himself. This is his so-called "iceberg theory," which he originally described in The Green Hills of Africa. "The Killers" raises many questions which are not answered in the story, but presumably Hemingway knew all the answers. Here are a few questions:
How did the hit men know Ole Andreson was living in Summit? Obviously these men, who were only doing the job as a favor to a friend, had been told by the friend that Ole was living there. But that doesn't answer the question. How did the friend know?
Was Ole Andreson the big Swede's real name? If he was on the lam, why didn't he just change his name? Maybe he did, and Ole Andreson was an alias.
That raises another question. Why do Max and Al call each other by their names? Aren't they giving away important clues? Or are these names also aliases which they made up to deceive whoever would be in the diner? Or does the fact that they are calling each other by their real names indicate that they intend to kill all witnesses at the same time they kill Ole? Hemingway would have had to give them names in order for the reader to tell them apart, but would Hemingway have thought of giving them false names?
The name Summit indicates that this town is on a mountain. What sort of enterprise goes on in that region to support a town big enough to have a streetcar line? I think it would have to be either mining or lumbering. Ole must be working there. He obviously doesn't have much money or he wouldn't be living in a cheap rooming-house. It would seem that, because he is a big man who does hard labor, he would be hungry and want to eat dinner as soon as possible after work. Since dinner is not served until six o'clock, that is why he would arrive pretty regularly at six. However, business seems very slow on this evening. It is probably a Sunday, and Ole is not hungry because he wasn't working that day.
What did Ole do that made the hit men's "friend" want to have him killed? Hemingway must have known the answer to this? Since Ole was a boxer, it seems likely that he took a dive when he wasn't supposed to do so and thereby cost some gambler a lot of money. Or, on the other hand, he may not have taken a dive when he was supposed to. That would suggest that Ole was the favorite in the match. Hemingway wrote a great story about crooked boxing in "Fifty Grand."
How did the friend get the erroneous information that Ole ate at the same lunch-room at the same time every night? This certainly sounds like a clue! Who would know that Ole ate there frequently but thought he ate there every night? One possibility is the owner himself, Henry, who is not depicted in the story. Does Henry have a reason for not being there? Or does he only work in the daytime and leave the night business to George and Sam the cook? The place is called Henry's Lunch-Room. Maybe lunchtime is the peak business time, so that's when Henry works there.
These are all things in the 90 percent of the iceberg that lie beneath the surface. It is natural to wonder how Hemingway would have explained them, assuming that he knew. There are many other such questions about this story, of course.