A common misinterpretation is to take Jesus' words about Elijah literally as predicting a future physical return of Elijah before the Messiah, ignoring the disciples' realization that it referred to John the Baptist already come and suffering as Elijah would; this overlooks the New Testament's emphasis on prophetic fulfillment through John's ministry in the spirit of Elijah, leading some to expect a separate end-times Elijah apart from John's preparatory work.
Matthew 17:13
King James Version (1769)
13 Then the disciples understood that he spake unto them of John the Baptist.
In this verse, the disciples grasp that Jesus' reference to Elijah 'who was for to come' points to John the Baptist, affirming John's role as the prophesied forerunner who prepared the way for the Messiah by fulfilling the spirit and power of Elijah, as prophesied in Malachi 4:5-6, thus highlighting how Jesus identifies John as the Elijah figure in a typological sense to usher in the kingdom of God.