The sudden shift or a sudden change in a communication badly affects the discussion or communication between the people who were in the communication. The flow of information and the interaction changes in such cases.
When we interfere a discussion in the middle or there is a shift in the communication strategy, it affects the communication a lot in terms of information, speech context, speech style and many more. The message delivered is also stopped and some other conclusion is drawn. The responsibilities of the speaker is also hampered.
You must be able to cite the source of the information given. This is to verify the accuracy of the research behind the information, to make sure that it's from somewhere reliable.