When a few helicopters fly by the gargantuan the helicopters are not very large in size.
But when the gargantuan grabs a helicopter out of the sky, suddenly.the helicopters are much larger in size.
When the Green Gargantua first attacks the line of tanks. It picks the tank second from the left ant throws it. Cut to shot of it landing on a house. Cut back to the Gargantua and it picks up the same tank and throws it at another house. The same thing happens for the tank on the right.
In the scene where a helicopter is used to lure the green gargantuan into the laser attack, the wire used to suspend the model helicopter can clearly be seen.