Michael J. Fox cast as guest star in season 3 of Apple TV+'s 'Shrinking'

The season 2 finale was a Thanksgiving-themed episode and served as an on-screen reunion with Segel's How I Met Your Mother co-star, Cobie Smulders. 

"Shooting with Cobie again was a dream. We did nine years of How I Met Your Mother and that was never part of the Marshall/Robin dynamic so it was this gap in our acting experience together. I think the reason people are reacting to it, the reason it feels like, 'oh, I would like to see them together again' is this is a scene where two people are meeting for the first time, but you’re supposed to have some other sense of, 'whoa, what’s going on there?' I think what is going on there, which is so cool and how acting works, is that we knew each other for 10 years in our most formative years, through thick and thin and becoming who you are," the actor told Variety. "Then to be standing across from each other as full-grown adults saying, 'look at us still here, still standing.' These are two characters having been through some tough times and Cobie and I have each separately been through some tough shit side by side."

As for season 3, he shared, "I’m allowed to say our words for Season 3 are 'moving forward.' So that’s all we really know so far. Season 1 was grief, Season 2 was forgiveness, and Season 3 is moving forward."

The first two seasons are streaming on Apple TV+.