The slot car Tattoo is racing around the track is orange. When Mr. Roarke approaches him, it has changed to red. Right before Tattoo departs and returns from answering the door the car is now blue.
Race cars do not have, nor need a speedometer.
Tattoo tells Roarke that it's a beautiful day, at the beginning, and he agrees; however, the skies were overcast and completely white behind them, as it was very cloudy in Los Angeles the day they filmed.