When Grissom and Sara are tracing the blood-trail from the boy hit by the cab, they are in one scene where you see thunder-clouds, and you can hear some thunder in the background, and it's getting dark. In the next scene they have arrived to the park, and it's more or less in the middle of the day, and the sun is shining from a cloudless sky.
Greg tells Grissom that he's working on DNA from Catherine's rape case, but it is later revealed that Catherine has several days off for her daughter's birthday.