Character mistake: When Henry is describing the fishing reel he bought for his girlfriend, he said, "with jeweled escarpment" actually it is a 'jeweled esCAPEment" not esCARPment. An escarpment is a long slope off a plateau. An escapement is a latch/release mechanism that you would find on a device like a fishing reel.
Character mistake: Days after Drew's death (Roy and Johnny had two days off after Drew's death), during the meeting that Brackett has with the four paramedic units, one of 59's guys asks, "What do we do when we have this overload situation on the same frequency? Two squads, like 51 and us today?" The situation with the frequency did not happen "today" as he said, it happened at least three days prior.
Character mistake: When John-Boy reads the nursery rhyme "Simple Simon" to his nephew, John-Boy points to the colorful illustrations in this book and tells John Curtis, "See, that's Simple Simon, he's a bear." This is incorrect. In the illustrations, Simple Simon is a donkey, and it's the pieman who is a bear (he's wearing a chef's hat and apron). (00:40:50)