I'm a bit late to this party, but I just read that part last night, and immediately thought of this thread.
i'm not sure what decade this particular part was happening, but, if the whopper has sauce now, it didn't then.
I didn't think it was an error though. It might have been a regional term referring to the ketchup and whatever else was on a whopper! But I actually read it as a kind of put down of people special ordering something that comes a specific way (like a Big Mac without a pickle). Basically, inferring that customers didn't even know where they were or what they were ordering. They were ordering a whopper and "special ordering" without the Big Mac special sauce.