Yesterday, a Berlin bound 757 had to return after burning fuel because it blew a tire that resulted in an engine fire while taking off. Passengers reported "fire balls" coming out from under the wing after a loud noise. The crew said the engine then returned to normal but they returned as a cautionary measure.
Today, another United flight returned after smoke was detected in the cockpit which United later described as "an unusual odor".
Interesting way to twist things and it sounds like United is now paying script writers. Yes, please & thank you, I suppose the smell of smoke is indeed unusual cockpit odor.
Perhaps it was the crew making "smoors" over the coals or a Qantas crew having an "outback with prawns and ribs on the barbie" ??