I got this message from Martin Ross, who runs that 'Columbo' fansite you'll find linked to the left:
You probably spotted it or a similar cross-Abrams hook, but Agent Dunham had a couple of Oceanic Airlines tickets in her paw on Fringe Tuesday.
I haven't seen it yet m'self. I DVR'd it Tuesday night as I made ready for work. But then I took the train to Connecticut right after work for the holiday. So I'll check it out tomorrow.
But I guess that puts 'Fringe' "officially" into those other versions of the TV Universe!