After Murtaugh has a shave in the bathroom, he then goes out onto his boat where he is met by Cole. His 5 o'clock shadow has returned.
At the end of the episode when Murtaugh comes home and is discussing the end of Riggs's case with is family, in 1 camera angle cut his sunglasses are hanging off his shirt collar, while everyone other shot doesn't show any sunglasses at all.
In the opening scene with Riggs being wheeled into the hospital, Murtaugh is shown with a this, slightly disheveled goatee. This is supposed to take place the same day as the end of the finale of Season 2, in which Murtaugh had well curated and maintained facial hair.
In the last episode of season 2, Riggs is shot in the chest, next to Mirandas grave, but in the photo on Murtaughs boat, there is no gunshot to the chest, and it looks like he's been shot in a forest.