In real life, the three colliding bodies would convert their kinetic energy into heat and combine into a very hot body. Sort of how we think the moon was create

In real life, the three colliding bodies would convert their kinetic energy into heat and combine into a very hot body. Sort of how we think the moon was created, from a Mars-sized body colliding with Earth long ago. But in a numerical simulation, usually what happens is that three bodies on a collision source approach one another but, because of the limitations of numerical differential equation solving, suddenly fly away from each other in a rather non-physical way, and with more energy than they had to begin with. The tl;dr: most of the funny effects in a simulator arise from the limitations of numerical simulation methods, and many of those aren't representative of real physics.