Jamieson, Fausset and Brown on Exodus 4:20

20. Moses took his wife and his sons, and set them upon an ass--Septuagint, "asses." Those animals are not now used in the desert of Sinai except by the Arabs for short distances.

returned--entered on his journey towards Egypt.

he took the rod of God--so called from its being appropriated to His service, and because whatever miracles it might be employed in performing would be wrought not by its inherent properties, but by a divine power following on its use. (Compare Ac 3:12).