On the night that He was arrested, Jesus went to the Garden of Gethsemane to spend some time with God in prayer. The traditional site of the Garden of Gethsemane sits at the base of the Mount of Olives just across the Kidron Valley from the city of Jerusalem. Today, a Roman Catholic church, commonly called The Church of All Nations, is built on this spot.
If you stand on the steps of the Church of All Nations and look toward your west, you see the view that is depicted in the picture at the top of this post. I took this picture last September while visiting the site. It is a picture of what is commonly called the Golden Gate. This gate was built in the 6th Century AD on the ruins of another gate that dated to the Second Temple Period. During the time of Christ, this gate served as an entrance to the Temple Mount area for people that came from the east (Bethany, Bethpage, etc). It is not unreasonable to assume that Jesus, his disciples and many other people of that day went through that gate. As you can tell from the picture, the gate is not far at all from the Garden of Gethsemane.
Let's look at the picture a little differently. Imagine it is the middle of the night. Except for lanterns or torches that are illuminating the rock walls, it is completely dark. And, it is quiet. So quiet that Peter, James and John could fall asleep....twice. Now, let's read the passage from Matthew 26:
Then He came to His disciples and said to them, “Are you still sleeping and resting? Behold, the hour is at hand, and the Son of Man is being betrayed into the hands of sinners. Rise, let us be going. See, My betrayer is at hand.” And while He was still speaking, behold, Judas, one of the twelve, with a great multitude with swords and clubs, came from the chief priests and elders of the people. - Matthew 26:45-47
From the passage, we know that the multitude came from the chief priests and elders, and it is probably safe to assume that they were in the city. If so, then Judas and the rest of the multitude could have come out of this gate.
Jesus could look up the hill and could see the lit torches that they would have been carrying. He could probably hear their voices and the clanging of the soldiers armor.
He knew that they were coming. He could have run away. But He didn't.