My first impressions of Mouse PI are less focused on the gameplay - it's your standard post-Doom-4 boomer-shooter type deal, you dash, you double jump, you kick, it all basically works, the rubberhose guns are amusing - and more on the story. Now, I'm not super familiar with film noir, so I can't talk about how it relates to the wider genre, but I have watched Who Framed Roger Rabbit and I'm aware of the implications of Toontown. I feel as though something similar is going on here: the unrest between the mice and shrews of Mouseburg, especially as depicted in the collectible newspapers, feels like more than just background noise. There's something allegorical going on there, and it leans into something similar I think to Eddie Valiant being noted as the most toon-friendly detective in LA in WFRR: the private detective as a force for positive social change, helping people where the police won't. Also definitely wasn't expecting allusions to the World War(s), nor for them to recur in the actual plot rather than just being a gag about the 'Quite Big Affair'.
Too early to tell exactly how it'll pan out in the wider story, but I'm interested in seeing where it goes.