Did those 'running in the tunnel' things really happen?

sure it probably happened, probably not actually in most cases, obviously, but the idea of this scene just shows the general extent to which the nazi's might go to. safe to say, there were probably a few officers who would have objected to this, and would have said so, but then they would have ruthlessly carried out the executions anyway. just following orders, of course.

I wouldn't be surprised if this sort of thing has happened in every single war known.

The tunnels where originally shooting galleries - they were regularly used for executions in Nazi occupied countries.

The practice of making the intended victims "run for their lives" was relatively frequent on Nazi's part as part of their anti-insurgence tactics. Reasons for that varied wildly (and, to be honest, that had not been a Nazi invention!). In few cases the "race" was genuine - people who reached the "end" were sometime spared (this meant they were sent to prison camps, not let free!!). Sometime it was just sadism - particularly when the execution was not a formal affair like that shown in the movie but part of some "search and destroy" operation against partisan units in the wild (burning villages suspected of helping partisans and massacring all the inhabitants was an almost daily occurrence in the Eastern Front and in Yugoslavia, and became quite frequent in Italy between 1943 and 1945. It occurred few times in France too.

In most cases, staging these theatrics was done mostly for the benefit of the executioners. Killing harmless people is not something most people do naturally, and it was often needed by commander to "involve" their soldiers giving them the impression than the victims had a chance to escape, or - to the reverse - making them feel more and more "part of the play". By the way, liberal distributions of alcohol before and after the execution was very common.

People often thinks that troops fighting this kind of "dirty wars" were some kind of robots who simply obey order automatically, but the truth was quite different. My dad had the misfortune to watch in 1944 (as a mere 10 years old) several executions of suspected partisans near his village in Northern Italy, before ending up, with his entire family, as nearly being the target on one, and the behaviour of killers and victims was often extremely contradictory, from the trooper laughing in the face of the terrified chap begging for his life, to the officer telling the kids "don't watch" while his troops were doing the bloody job. Drunkenness, chaos and madness were the rule, not the exception, and people survival was often at mercy of the sudden decision of individuals, not "orders".

During Pinochet's dictatorship in Chile they used a similar method. They told the prisoners to run so the officers say afterwards that they "had" to kill the prisoners because they had tried to escape.

I believe that such sports-like executions might have happened. But what I found strange was that the German officer himself was standing almost in the line of fire, while his troops were shooting at the prisoners. Such recklessness from an officer is hard to believe.