How did this teleportation happen in DN 16?

SN 51.22 explains how to do levitation. http://lucid24.org/sn/sn51/sn51-022/index.html

And it's not just the Buddha, or famous chief disciples. Anyone who develops a strong enough 4th jhana has the potential to master this ability.

Those who have achieved Nirvana have many magical powers. It did not happen metaphorically...It happened for real.

It's always better to take what ever metaphorical in line with the Dhamma, as a reminder for thinking in dhammic ways, or to nourish Pasāda or Saddhā, as sample of path and gain of fruits, than to try to nail down phenomena in terms or real, because what is non-act-ually real? It leads and will lead and cause suffering grasping thing like in common way. As there is a Austrian proverb: it would just turn out into "controversies on the empires beard". At least, the Sublime Buddha taught that trying to imagine the transcend powers of the Tatagatha, conting also for Arahats, would lead to become crazy. And that's also said to waste not time in do this instead of turn to the path.

So in this way it might be enough for letting go of this instance, and step on further with things actually bringing benefit and how and what is real, or how things may arise and decay, will become clear anyway, as soon as done the task, of which isn't investigating to rebuild a history from far, far away.

Now since knowing that it's just a nice sign along the path but not it's aim, it's good after that (un-)rest to go on -- because time is running fast and human blessed existence is difficult to ever archieve: the water level already increases rapidly and the fire mass of suffering comes rolling on from behind.

[Note, as it would serve for it as well, it's not given for stacks, exchange, other world-binding trades but for release]

It's not real story of man crossing over a stream, but the wisdom of going further, to the farther shore of Truth. Don't believe in supernatural stuff. Enlightenment means losing everything, your senses, body, mind, sens of I and also spiritual powers, if any.

✓'Those who cross a river or stream have built a bridge and left the marshes behind. While some people are still tying a raft, intelligent people have crossed over.'"

::Meaning is simple:: When man start to the way of wisdom, the purity of stream enters through the gate of 💓. When one surrenders totally to it, he become one with stream. Then that river started to going towards the source, in reverse manner. Many disciple put hold something as goal, misses it for crossing over. Like holding onto the bridge, the raft etc. But, learned one go with the stream till the end without holding anything, not even boat. He place his foot on the farther side and leave alone the boat.Thats Arhatphala, Nirvana, Crossing over.

Also in one instace Buddha said, If I try to swim I get whirled about, I stay as steady, I drowned. So without swimming and remain steady, I find myself to the other shore. How? The truth is 'thou' are already there. But due to ignorance, you thinks you are in the stream. I hope it gets clear. ✓Upanishadic dictum also says the same: "Thou' are That." Thou' are not body, senses, feeling, sensation, perception, councioussnes. But thou' are supreme. Awake from sleep of ignorance and throw away what is not yours!

Piya Tan's translation and commentary of DN 16 has two footnotes:

459. The various texts differ regarding the details of the Buddha‘s crossing the Ganges. They however agree that he uses his psychic power to teleport himself and the order across the river. The redactors added this episode despite the Vinaya rule against the public display of psychic powers (Pāc 8 = V 4:25): see Kevaḍḍha S (D 11) = SD 1.7 Intro (3.3). The Pali texts apparently regard the episode as ―symbolic of the Buddha‘s attainment of the ̳other side‘ of transmigration, ie extinction (nirvana), by the power of meditation‖ (Warder 1970:71).

460. According to the Sarvastivada account, only the Buddha crosses the Ganges by his own power. The monks swim across while other disciples build a raft (Waldschmidt 1950-51:158). The imagery here is obvious: the Buddha has crossed the ocean of suffering; his immediate disciples, the monks, crosses the river of suffering using their own effort; and the lay disciples are working at their own means of the salvation, the raft. On this verse, cf Dh 85.

In Acintita Sutta: Unconjecturable (AN 4.77) it has mentioned that there are four things which are unconjecturable.

"There are these four unconjecturables that are not to be conjectured about, that would bring madness & vexation to anyone who conjectured about them. Which four?

"The Buddha-range of the Buddhas(1) is an unconjecturable that is not to be conjectured about, that would bring madness & vexation to anyone who conjectured about it.

"The jhana-range of a person in jhana...(2)

"The [precise working out of the] results of kamma...

"Conjecture about [the origin, etc., of] the world is an unconjecturable that is not to be conjectured about, that would bring madness & vexation to anyone who conjectured about it.

"These are the four unconjecturables that are not to be conjectured about, that would bring madness & vexation to anyone who conjectured about them."

Notes

(1.) I.e., the range of powers a Buddha develops as a result of becoming a Buddha.

(2.) I.e., the range of powers that one may obtain while absorbed in jhana.

As the blessed one said, I cannot think of how it would've happen. But with the emerge of the quantum physics, scientists built theories and tried to explain such teleportation behaviours. They have observed similar behaviour in quantum fields but unable to explain why and how it would've happen.

Bhikku Samahita discusses some of these behaviours found in Tipitaka in related to quantum mechanics through this video: Early Buddhism, Quantum Physics, & Relativity