During the Credits
There are no extras during the credits of Halo Wars 2.
After the Credits
There is a stinger after the credits of Halo Wars 2.
The disarmed Halo that leaves the Ark via slipstream space is seen mysteriously dropping back into normal space. Professor Ellen Anders then leaves the control room and returns to the surface. When outside, Anders is shown walking in a wooded area on the Halo until she is confronted with a Forerunner Guardian. She then comments to herself that it may have been safer staying on the Ark as the scene ends.
Special thanks to straga27 for the stinger submission!