Zach Galifianakis hits the road to do celebrity interviews to restore his reputation.
Between Two Ferns: The Movie is basically a series of excerpts from celebrity interviews, linked together by a formulaic road trip story. It literally follows the same story beats of every other road trip movie made, with no attempts to liven it up at all, because that isn't the focus of the film. All the road trip storyline is tasked with achieving, is carrying our characters from one interview to the next. To that extent, it does as advertised.
Two Ferns is a story of two parts, with the interview and road trip elements both being done vastly different in terms of cinematography, music and tone. The interviews have the usual zero background noise or ambience, combined with a purposefully antagonising, dry and sarcastic sense of humour. The road trip, on the other hand, is lively, colourful, accentuated with frequent musical pieces and over-the-top acting performances, but is far less memorable, with a lower success rate on the humour side of things.
There are a huge number of high-profile cameo performances involved, from David Letterman, John Legend, Matthew McConaughey, and Keanu Reeves, to Brie Larsen, Paul Rudd, Tessa Thompson, Bemused Kibblesnatch, and Peter Dinklage. You would be forgiven for thinking that this entire mockumentary was filmed on the set of Avengers: Infinity War and Endgame with the amount of Marvel MCU actors involved. As would be expected, the interviews for the most titillating portions of the total product, with a great mix of dry wit, offensive questions, and deadpan reactions from the actors in question. It should be noted that there are outtakes shown in the credits that (in this humble reviewers' opinion) were funnier than what was shown in the film. Something about the more organic and authentic reactions and the to-and-fro between them and Galifianakis having a greater appeal.
In all honesty, the only real appeal of the film comes from the interviews, and many of the full interviews that are partially shown here are available on YouTube. The narrative that surrounds these interviews is far less engaging. It telegraphs its intentions in the dialogue that lacks any sense of subtlety, which means there is no sense of surprise when characters act a certain way later in the film. The over-explained plot points remove any mystery and reduce the impact of the payoff.
Between Two Ferns: The Movie is self-aware, and some of the comedic elements that revolve around that do work well. It is very aware of what the appeal of the show is, and it uses it in the most hamfisted way possible. It gets the laughs, but it does struggle to maintain that level of mirth throughout the 82-minute runtime. The whole story is of no real consequence and offers nothing to analyse or think about. I'd recommend looking for the full interviews on YouTube; it's a better use of your time.