"I don't have any weaknesses." It's important to be honest about your weaknesses and show that you are self-aware and willing to improve.
"What does your company do?" It's important to research the company before the interview, so you can demonstrate your knowledge and enthusiasm for the organization. Asking basic questions like this can make you appear unprepared.
"I left my previous job because I didn't get along with my boss/co-workers." Speaking negatively about past employers or colleagues reflects poorly on you and raises concerns about your professionalism and ability to work in a team.