i think you cant do both at a time, IMHO with followingRedirects() it just does a get request until there is no redirection anymore and you dont have access to the previous request headers to assert on.
if really necessary i would split the test into two:
it_redirects_to...()
{
//do not use followingRedirects() here and check assertRedirectToRoute()
}
it_contains_..._on_the_redirect_page()
{
//use followingRedirects() and use assertViewHas()
}