Corrected entry: Michael Fassbender quotes lines from a poem, Ozymandias. He states the poem was written by Byron, when in fact it was written by P.B. Shelley. (01:19:00 - 01:19:50)
Corrected entry: At the end David regurgitates the alien embryos and places them in the refrigerator with the human embryos. The thing is they are in exactly the same matching capsules as the human embryos and are an exact match for the compartments and fit perfectly. Impossible as he would have no idea of the refrigerated compartments or the layout of the ship.
Correction: All this shows is that David stored his facehugger embryos in the same configuration as what human colonists would for human embryos. For all we know it could be a standard size and shape. He knows the Covenant is a colony ship so he could have speculated they would have an embryo freezer.
Corrected entry: The computer on board the ship mistakes David for Walter. This makes no sense as while a human being could be fooled by his appearance or his voice, a computer with detailed sensors and possessing the exact details of David's composition would not be fooled simply because the two "look" and "sound" alike. In fact, Walter, being a newer and more advanced model, should be composed of different chemicals and materials than the earlier manufactured David making it even less likely that the ship's computer would have mistaken the two.
Correction: Makes way too many assumptions about the manufacturing of either one.
Furthermore, we do not know exactly how the ship is supposed to be identifying the androids in the first place.
I feel like I already corrected a similar mistake. David is less advanced, but cleverer than Walter. The correction is right in saying there are too many assumption being made. Who knows what David did to be more like Walter, that might even be easy for a highly advanced android. Who knows how advanced and sophisticated the computer sensors are to detect an imposter android. I didn't think the computer or anything much is made with many defenses against sabotage. Its a peaceful universe. Also don't really remember but the first time David enters the ship couldn't he already have modified the computer? Hacked it?
Well, we do know that Walter is constructed much differently that David. David uses what he thinks is an android-lethal move on Walter, and David thinks he has killed Walter. Moments later, David is astonished to see Walter not only alive but ready to do battle again. At this point, Walter even says, "There have been a few upgrades since your day." Which means that Walter is different in ways that even David didn't imagine. So, the original post is correct: Even a cursory security scan of David would have instantly revealed that he wasn't Walter.
Corrected entry: David would not have the time to beat Walter, change into his clothes and cut his own hand off in the time given to meet the shuttle.
Correction: Actually he has plenty of time. When the two androids fight we can see that David reaches for a knife, then there is a cut and we see the survivors of the Covenant outside, waiting for the shuttle. In the meantime it is absolutely possible that David killed Walter, changed into his clothes and chopped his hand off. That is absolutely possible within two minutes.
Corrected entry: David cuts his long blonde hair. When we see him next his hair is the exact same colour as Walter's, with no time to colour it.
Correction: His hair hasn't changed colour. It's just the dim lighting that makes it look like a different colour.
Correction: This is an intentional error and is addressed later in the movie when Walter corrects David, stating that "When one note is off, it eventually destroys the whole symphony." It's meant to suggest that a flawed creator (David) can't create a perfect being (David's experiments with the xenomorphs).