Iam from germany and my english is not good. Can anybody correct my short text!!!?

Your English seems good to me. It's better than my German! Only this sentence is broken: "Since it were for many test subjects to unpleasant that they didn´t intervene therefore they were not willing to answer our questions." There are grammatical errors in there, but more importantly, it is just an awkward way to say what you're trying to say. (I'm a writer. I'm sorry.)

In executing our experiment, which we called "the drunk driver," there were small problems. For example, some test subjects didn't want to respond to our inquiries. For some test subjects, the idea that they didn't intervene was so unpleasant that they didn't even want to talk about it. Some test subjects tried to bluff, rationalizing their intervention or their non-intervention. For example, a male test subject said that he did not intervene because our alcohol bottles might have been filled with water. Also, we did not have enough equipment to record all test subjects' reactions. More than one camera and a microphone would have helped. Many of our observations were lost because we could not film the reactions from different perspectives at the same time.

For some reason, "drunken" is rarely used. I changed it to "drunk" because "drunk" is much more common, especially when talking about drunk drivers.

"Bluff it out" is not the expression. Just "bluff."

"Justify" is a big word and, actually, you used it correctly! But I changed it to "rationalizing" anyway because "rationalizing" is even more correct. (I know, English sucks!) People can rationalize things for which there is no logical justification.

Good work! It sounds like a fun experiment, too, actually. I hope you had a good time.