There are experimental aspects on the MCAT but it is not like the SAT where an entire section is experimental.
Instead, when a writer writes a question they project out the difficulty of a question. For example, If I were to write a question and I feel 90% of students should get it write but when the test comes back only 10% did then AAMC MIGHT make adjustments. Usually the question was poorly worded and from what I have been told it is thrown out. I was told that entire passages are very very rarely thrown out.
Hope this helps
Radon222