While How I Met Your Mother’s saddest scene featured a devastating twist, the sitcom's creators went to extremes to ensure that this shock was a surprise for everyone involved. For much of the show’s run, How I Met Your Mother was a fun hang-out sitcom that managed to keep the genre’s oldest institution, the much-maligned laugh track, alive in the '00s. However, like many great sitcoms, How I Met Your Mother could pull off some devastatingly dark moments from time to time.

https://screenrant.com/how-met-mother-tragic-twist-segel-tricked-real-acting-explained/