Suppose someone knows well the theory of connected reductive groups, over an algebraically closed field or more generally over any field, say for instance most of the content of Borel-Tits.

Is there a reference on reductive groups with an emphasis on the issues that arise when working with non necessarily connected reductive group ?

I am thinking of something that would give an overview of what part of the theory for connected reductive group extends with little adaptation to the general case, and what part becomes hopelessly wrong in the general case. Also, your own insights on the subject will be welcome as answers.