Continuity mistake: In the Tech Noir Bar, the same woman - blonde with a pink or orange dress - must have come dancing with her twin, because while she's sitting behind Sarah Connor when the laser beam is pointed at her, she's also dancing near Arnie. The T-800 moves past her when he sees Sarah Connor and moves to shoot her. (00:35:05)
Continuity mistake: When The Terminator's stolen police car is shown up close in the parking structure, the motto on the left side of it reads "to care and to protect." After the car crashes, you can see the motto on the left side again, but this time it reads "Dedicated to serve." The car's trim and position/orientation/color of the police emblem change as well. (00:45:50 - 00:50:20)
Continuity mistake: Arnold looks up Sarah Connor's address in the telephone book. The telephone book address has 4 digits, but he goes to a house that has 5 digits on it. (00:15:00)
Continuity mistake: At the start of the film when we first see Reese arriving, the drunk homeless guy is holding a bottle in his left hand, then the camera continuously switches between Reese's arrival and the old guy, in these shots, the bottle keeps changing hands from left to right, then back to left. (00:06:40)
Answer: Its simply a child being a child and playing, but more than anything, showing the innocence of the children that inspite of the near death of the human race all around them, there's still time to play and be... human.
GalahadFairlight