Riding the king's mule showed high status. An ancient text from Mari advised King Zimri-Lim to follow royal protocol by riding in a donkey cart. David's sons rode mules (2 Samuel 13:29; 18:9). Similarly, Zechariah predicts that Israel's king will come "riding on a donkey, on a colt, the foal of a donkey" (Zechariah 9:9), a prophecy fulfilled by Jesus (Matthew 21:4–7; John 12:14–15). When Solomon rode David's royal mule, it showed that David approved of Solomon becoming king.
The Gihon Spring was the main water source for Jerusalem. It was just outside the city’s eastern slopes. People often gathered there, so Solomon’s anointing would be widely known. But those who supported Adonijah at En-rogel could not see it.