Activities and Nodes in One Calendar
Drupal Views starts off with a base table - do you want to look at:  User, Nodes, CiviCRM activities and so on.

So if the base table is Nodes, then it's looking at nodes for the date info and displaying them.

If the base table is CiviCRM Activities, it's looking at those for the date info and displaying them.

But currently in Views you cannot combine this data. They are two separate views.

Back in the forums there has always been discussions about combining Drupal node dates and CiviCRM event dates - it's the same problem.

So out of the box there is not really a solution for this.