Dr Brown tells the travel agent his new address is 2179 Dearborn, but when the parcel arrives the number is 2719. The number on the wall of the house is 2179.
While cooking breakfast, Dr Brown leaves a flapjack pancake on the electric cooking griddle but nothing burns.
Dr Brown should have cashed in the travel tickets instead of handing them to a couple getting divorced.
During the church service, they are supposed to sing hymn #31. Dr. Brown opens the hymnal to the middle of the book. Given that hymns are numbered, #31 would be very close to the front of the hymn book and not the middle, unless there were only 60 hymns in the book, which was too thick for only 60. Someone as smart as him can surely find #31 even if they're not familiar with a hymn book.