‘And they went forth and preached everywhere, the Lord working with them and confirming the word by the signs that followed. Amen.'
This final summary indicates the obedience of the Apostles to the Lord's command, and the fulfilment of His promise about the signs that would follow. They preached ‘everywhere' and ‘the Lord' worked with them, confirming the word by signs. He is no longer Jesus but ‘the Lord'. These signs may have included the evidence of the power of the Holy Spirit at work in the conversion of men and women to Christ, but also included the signs that would ‘follow' as stated in Mark 16:17-18. Both Jerusalem and the world were made to witness His Kingly Power at work visibly on earth (Mark 9:1; Mark 14:62).
‘Amen.' So be it.
Note.
The shorter ending reads, ‘and all that had been commanded them they briefly reported to Peter and those who were with him. And after this Jesus himself appeared to them, and from the East as far as the West sent forth through them the sacred and incorruptible proclamation of eternal salvation.' It may have been known in the late first century AD to Clement of Rome, for when he spoke of Paul he said, ‘After preaching both in the east and west, he gained the illustrious reputation due to his faith, having taught righteousness to the whole world, and come to the extreme limit of the west' (Letter To The Corinthians Mark 5:6). But the last phrase in the shorter ending does not have the simplicity of the Gospels. It sounds like second generation Christianity (in contrast with the longer ending).