Battle Arena portal

As E.T. flew in the sky on a phone-like vehicle, a round object with red, yellow, blue, and green flags was present on the ground behind him. (WC: Supergirl Meets E.T.)

Behind the scenes
Although not remarked in WC: Supergirl Meets E.T., the portal seen in the background is a portal into a Battle Arena. No Battle Arena exists in NOTVALID: LEGO Dimensions for the Doctor Who franchise.