Director Peter Cattaneo works from a script that Jeff Pope adapted from the 2015 memoir of the same name by the real Michell (Michell was in his 20s when the events happened and Coogan is almost 60 so it's far from a documentary). I don't think it's a spoiler to say that the middle act had me thinking of the lyrics to the nursery song Mary Had a Little Lamb. And here's a fun bit of trivia: the penguin is named Juan Salvador Gaviota, which is the Spanish translation of the 1970 novel Jonathan Livingston Seagull.
Federico Jusid is listed as the composer but I found only this short suite of his score on YouTube (sorry about the ad). There are a lot of songs in the movie, though, compiled in this playlist on Apple Music.
This YouTube video (with multiple ads) is fascinating and I recommend it for after you watch the movie. I learned from it (not a spoiler) that there were two penguin actors, who are mated in real life, plus one animatronic penguin and one puppet penguin.
With 31 producers, this movie earns a spot about halfway down my Producers Plethora Prize list.
Coogan was last blogged for two pictures in my list of Random food movies plus Stan & Ollie the following year, Pryce for The Two Popes, Pope for Stan & Ollie, and Jusid for The Last Suit. El Jaber and Carrocio are new to me. Cattaneo has worked a lot since he was much lauded for The Full Monty (1997) but I haven't seen any.
Rotten Tomatoes' critics give it only a C+ with their 78% average, while we and its viewers award it a solid A at 95. On Kathleen's hearty recommendation we rented it on Apple TV on May 21.