漏掉 implies accidental omission. Compare: 遗漏 (yílòu, formal: to omit/overlook), 落下 (là xià, to leave behind), 跳过 (tiàoguò, to skip deliberately).
grammar
掉 as a verb complement indicates something is gone or removed: 丢掉 (throw away), 忘掉 (forget), 删掉 (delete), 漏掉 (miss/omit). It adds a sense of loss or completion.
