Finally watching my Blu-Ray for Underwater (2020) and...
(1) A while back I came across multiple Reddit threads trying to figure out where Gunner Wright (Isaac Clarke, Dead Space), Will Eubank's friend, made an appearance in the film as a character he played in Eubank's 2011 film, Love. Folk made it seem like this was the hardest Easter egg to find in the film because no one could spot him.
Listening to the Audio Commentary, however, Eubank mentions that Wright is one of the two drill workers who don't reach the bulkhead before Norah (KStew) closes it. Wright is also the commercial voice at the end of the film greeting Norah, Emily, and Smith when they enter the main hall of the Roebuck ("Welcome to the Roebuck!"). IDK, it helps to buy movies instead of just streaming them if you want more information.
(2) One of the deleted scenes reveals that the helmet that Rodrigo (the token Black guy) had a huge hole in the corner of the protective glass. The final scene just shows him staring at the helmet forlornly then giving Norah one of the undamaged helmets. I feel like they removed that scene purely because the hole creates more questions than answers (specifically, how did Rodrigo's suit not get flooded). But, they also could've just rewritten his death if they really wanted him to be the first to die. Like, dude could've just stayed behind, but, eh. Shock and awe.
(3) In at least one version of Rodrigo's death, he says a "hail Mary, full of grace" prayer before his suit implodes and he dies.
(4) In the same scene Capt. Lucien reveals he thinks all of his crew is pretty much fucked. Smith asks him, "What are we looking at captain?" When he sees Lucien studying a map. Lucien says, "We're dead" and pats him on the back. Smith and Co. don't know French, which is why he says it that way.
(5) Eubank suggests, that if people wanted to, they could read into the idea that Capt. Lucien kind've went mad when he (and his old crew) was working on Shepherd Station after his daughter died. Just based on the Cthulhu references on the map in his old locker.
(6) For whatever reason, they did a lot of shooting with a real rabbit (they named "Little Paul"), then replaced it with a stuffed rabbit just to change how the actors would interact with it.
(7) The scene immediately after Rodrigo's death apparently contains a moment where Cthulhu (or "the behemoth") is nearby watching Norah right before she jumps onto the elevator. Effectively, this suggests the "deep ones" (or "the clingers") that constantly attack them are never far from where Cthulhu is and that it's stalking them throughout the film.
(8) Smith and Emily being the only reported survivors at the end of the film means none of the twenty or more evacuation pods that Capt. Lucien sent out at the start of the film made it to the surface.
(9) the majority of the film was filmed on practical sets (akin to Pacific Rim) and said sets were built on gimbals inside of an abandoned LOWES building in New Orleans.
(10) Love, The Signal, and Underwater might all take place in the same universe because of the appearance of Gunner Wright playing the same character (Capt. Lee Miller) from Love.