The Truck Stops Here

In this summer of big bad F/X extravaganzas, how on earth could Chain Reaction top Twister's computer-generated flying 18-wheeler? With the genuine article, naturally. For a scene in which a hydrogen explosion blasts a tanker past Keanu Reeves, filmmakers used air cannons to fire an actual truck past a stunt motorcyclist. ''We took all the weight we could off the truck,'' recalls stunt coordinator Walter Scott. ''We took the engine out. We even made tires out of foam rubber.'' There was, however, some postproduction digital finagling. (Fear not, Keanu lovers: The close-up of the tanker flying over his head was entirely computer-generated.) The finished scene is a smooth amalgam of actuality and technology. ''I'm not even sure what was computer and what was for real,'' Scott admits. ''It all looks so damn good.''