Roche Manager interview questions

The interview was lengthy. Questions to referral person was very lengthy and too detailed. How can your referral possible to remember joining date in previous company when you work there for 5 years.. HR was not really serious (giggling away) when asking questions to referral person

First of all, HR performed interview with me. Afterwards, I made a case study presentation to director level related with the job I applied. They sent me the topic earlier than the presentation time. Then I entered an evaluation center assessment.