Robotic Assisted Surgery (RAS) represents an important step forward in the field of minimally invasive surgery. However, the learning curve of RAS is steep, and a systematic planning of surgical robot setups should be performed to leverage the features of RAS. For this reason, in this paper we show the design and implementation of a mixed-platform collaborative system, creating an interactive virtual shared environment that simulates RAS during the surgery planning phase. The proposed system allows one or more experts to plan together the different phases of an RAS-based surgical procedure, while integrating different levels of immersion to enhance computer-assisted training. We have tested our system with a total of four domain experts. Our results show that experts found the system excellent in terms of usability and useful to prepare and discuss surgical planning with RAS.