Continuity mistake: When Harrison Ford meets Rachael again, he says she is not accurate because "she had green eyes." But when Rachael is being interviewed for the first time in the original, her eye is displayed on the monitor. The eye is not green. (02:16:05)
Continuity mistake: When K is at the food court and the three replicants start talking to him, he is standing at a table with a bottle of juice on it, as well as a small food tray, with a gap between them. When Mariette leaves the table later on and K has another look at the photos in his hand, the juice bottle and food tray are suddenly right next to each other. (00:44:25 - 00:46:10)
Continuity mistake: When K is at the food court, in the close-up shot of the photos when he is looking at them, a plastic spoon can be seen inside the food tray on the table. Around a minute later, when he is approached by Mariette and the two other replicants, the plastic spoon cannot be seen. Later in the scene, when Mariette looks at the photos K has in his hand, the plastic spoon has suddenly reappeared. (00:43:25 - 00:44:25)
Continuity mistake: Just after Niander Wallace is introduced, the scene cuts to a newborn replicant being dropped from a plastic container. The replicant lands on a mat, with her left hand next to the edge in the wide shot. The shot cuts to a closer angle of the replicant, where her left hand is further from the edge. (00:38:20)
Continuity mistake: When Wallace is feeling the newborn replicant, in the shot where he says "to preserve the clay", he moves his left hand around the replicant's face and the shot ends with his left thumb placed on the left side of her head. The shot changes angles, and his thumb is now touching the back top of her head. (00:39:00)
Continuity mistake: When Luv and Deckard are in the car on the way to Off World, Deckard looks downwards to look at his restraints, but in the next shot, his head is not lowered and is now turning his head towards Luv. (02:19:00)
Continuity mistake: When Lieutenant Joshi is instructing K to kill the replicant child, in the shot where Joshi asks if he's telling her no, her whiskey glass is on the windowsill, but when she says "attaboy" a few shots after, the whiskey glass is suddenly in her hand. Joshi wouldn't have picked up the glass in between shots because she was waiting for K to reply. (00:27:55)
Continuity mistake: When K is asking Deckard about Rachel, just after he asks what was she like, the shot cuts to Deckard where he has his glass tilted to the right. The shot cuts again where the glass is more tilted to the left. (01:53:05)
Continuity mistake: After Luv fires the missiles on the scavengers, K gets up, goes over to the car and reaches inside the activate the drone. When he puts his hand inside the car, he turns his head to the right, but in the next shot, his head is facing the car. (01:04:30)
Continuity mistake: When Wallace tells Deckard "Pain reminds you the joy you felt was real", Deckard rests against the back of the chair he is sitting in. The light above them moves away from Deckard, leaving him shadowed, but when the shot cuts to an angle behind Deckard, the front of his face is suddenly covered in light. (02:14:15)
Continuity mistake: K is shown to have a very thick stubble beard throughout the movie, but when he returns to the LAPD for his second baseline test, it is notably thinner than before. (01:16:35 - 01:23:05)
Answer: Think of any manufacturing process. Samples of new products are frequently created and then immediately destroyed. Also, the new replicant would require processing, training, etc. It was simpler for him to just dispose of the test.