Mr. Moustafa (older Zero) told the story as he remembers and so he is implementing aspects of his life working at the hotel into his story. This shows up in 2 major aspects.
First: Throughout the movie, many things are labeled and are always readable throughout the entire shot, often in uppercase. It begins with things throughout the hotel being clearly labeled, as expected for a hotel, but expands to various other things that Mr. Moustafa is remembering. Two quick examples are shown below. The first picture has the text “LOBBY BOY”, “HOLY BIBLE”, “MENDL’S” all displayed towards the audience when Zero is visiting the jail. Later, when the group is breaking out of jail, “CHECK-POINT 19 SUPPLY DEPOT” and ZUBROWKAN REGIONAL LINE” are clearly legible.
The reason for this is that Mr. Moustafa has spent his entire life around hotels by now and he is used to seeing things clearly labeled in uppercase. In fact, it might seem odd to him if something wasn’t properly labeled considering how many legible signs there are during the first few minutes of the film when we see the hotel in it’s current state.
Second: There is repetition in things that happen (often comedic). Two examples of this are: 1) when the Society of the Crossed Keys are calling each other and the interaction was almost exactly the same across the different hotel managers with their lobby boys, and 2) when visiting the church and each member keeps asking “Are you Monsieur Gustave of…”. Perhaps that this is not the true retelling of the story, but how Mr. Moustafa’s remembers it. Being a Lobby Boy, he was probably exposed to the same series of requests/sentences throughout the day. Perhaps he is so used to mundane things that some of the interactions began to sound the same to him.
I am not sure on this second point and I would like to hear other’s views on why there would be this type of comedic repetition in Mr. Moustafa’s story.