Max tells Liz that he is departing 'just after dawn'. But when he approaches the pod chamber to depart, it is bright noon sunlight outside with no shadows, long past dawn. In addition, Maria and Liz speak to Kyle in his room before Max reaches the pod chamber, and it is bright daylight in that scene too.
The blood that Liz and Max look at under the microscope is still moving, blood cells would have died quite soon after leaving the body, let alone surviving the length of time it took them to get back to Roswell.