FMC Technologies Engineering Graduate (Rotational Program) interview questions

Came to campus and there was a pre-interview social (Very important to schmooze at) took several hours. On campus interview was a full hour long with 2 interviewers. Typical personality questions for the 1st half, times you've worked in a group, led student projects, managed under-performing team members etc. The second half consisted of a technical interview where they asked simple and at some points even leading questions about cut-away 3D models. 2 week response time and an on-site interview. They have a group of about 6-8 people come on site with a plant tour. For some reason even though the graduate position is rotational it would seem like each department would pick students to interview. This was especially odd because some students at the on-site had more than one interview. The only thing I could guess is that it's because it would be their starting department, or because their hiring department doesn't know their head from their a*s. I would believe either.