When Jesus said to them is literally “when therefore oun he said to them.” But it is necessary to identify Jesus by name rather than by pronominal reference, since the last person referred to in verse 5 is Judas.

They moved back and fell to the ground (so also Jerusalem Bible) is fairly close to most other translations (note Revised Standard Version and New English Bible “they drew back and fell to the ground”). This statement emphasizes Jesus’ absolute authority in the situation; even those who have come to arrest him fall to the ground when he speaks. In some languages it is essential to indicate in which direction the soldiers and guards fell, whether forward or backward. To have them fall forward would seem strange, since they were moving backward. Therefore it seems more plausible to translate “and they fell backward to the ground.” This rendering would also seem to emphasize more the power of Jesus’ statement upon the crowd. Furthermore, if one uses an expressions such as “fall forward,” there is the possibility of interpreting it as a kind of obeisance or expression of reverence.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .