In every movie, the Species alien has been able to detect defective genes just by touching a potential mate, including Sara. But at the end of this movie, Sara walks away with a sterile mate when she was seeking a fertile one to continue her species, and they are holding hands. She should have immediately detected his sterility.
The doctor refers to Sara as being 3rd generation of the alien species but she's not, she's 2nd generation. Eve was created at the same time as Sil but her embryo was cryogenically frozen, Sara is Eve's offspring so that makes her 2nd generation.
Despite Abbot's lab being the scene of a fight between Sara and the half-breed, just hours later it is once again in neat and fine order, with the only exception being the broken glass in the frame. Look out for the main computer desk, which is the first thing to be trampled in the fight, only to be magically restored in the next scene.
When Sara is looking for the half-breed she starts out with short shorts and a pink tank-top but as soon as she arrives at the hotel where the half-breed is situated she is wearing black pants and a pink t-shirt.
When Dr. Abbott is lecturing the class, he seems to be confusing the T4 bacteriophage virus, which infects only the bacterium E. coli, with human virii when discussing whether it was created from human DNA.