Samira's cat inconsistently appears in her bag.
The beers (background prop) in the pub scene change as the camera cuts from Stella Artois to a different beer.
With its sharp hearing the aliens can hear the minutest of sounds while being very far but they fail to hear the breathing of a person or heartbeat which can be heard by a human ear close to the nose or chest.
Calling a code blue in a hospice center would not be appropriate as the patients there are known to be dying.
What does it matter if a generator makes a sound? As long as person is quiet, they should be safe.
The alien that chases Eric and Samira into the tunnels drowns after it's under water for a few seconds. The alien is an extremophile that was drifting through deep space on an asteroid, with no oxygen, so it would not have drown so quickly. One theory is that the creatures were sent by an alien race to wipe out humanity before invading, and hence would have been carried in some sort of spacecraft.
The military blow up the bridges to prevent the aliens from getting off the island despite the fact that the aliens are already on both sides. They were in fact blowing up the bridges, so boats could sail along the river, without the risk of creatures dropping from the bridges onto the boats.
The ferry carrying people away from the island is honking its horn as it moves along the river only attracting creatures along the shore. If the goal is protecting people, then the horns would have been disabled. However, it may be sounding its horn in order to draw creatures to the riverbank, and hence away from other parts of the city, where people are hiding.
The military helicopters tell people to not make noise within the first twenty-four hours yet it is not until 400+ days that the Abbott family realizes to use high pitch frequencies to hurt the creatures. The Abbott family, by random luck, found a very specific high frequency which hurts the creatures, they are not affected by general loud noise ; perhaps like humans are particularly affected by the noise of fingernails on a chalkboard.
As shown in A Quiet Place Part II (2020) and this film, the aliens cannot swim and are afraid of water. However, in A Quiet Place (2018) one of the creatures willingly goes underwater in the Abbott's basement for an extended period making it an aberration.
The aliens are known to be blind but when they are chasing a certain person, they stop at the edge of the pier, somehow knowing there's water below that and they would be hurt by the water. How do they know there's water below the pier? They surely don't have sonars (if they had, all the story would've been different). And surely all those aliens haven't mapped all around the city.
Eric is a English character, played by an English actor. When he recites Samira's poem, he reads a phrase as "simple maths." Samira is an American poet; she would have written "simple math."