I wouldn't really describe any of the questions asked as particularly difficult or unexpected. I think all the questions asked were fair, relevant to the position, and mostly focused on things listed in my interview. Since this was a technical position, I was asked about my experience with JAVA, SQL, and R.
Sample questions included things like "Give an example where you had to trouble shoot raw data?" "Give an example where you worked on a project that involved data integration?" "Give an example of a project you performed in Java?" "Given an example of a project where you worked with R?"