Harold Lloyd’s “Now or Never,” directed by Hal Roach and Fred Newmeyer, includes a memorable sequence in which he appears to be caught on top of a train.

The final impression is stunning and we might pass it off as something done “by crazy movie people in the crazy ‘20s.” But these folks weren’t so crazy at all.  This 2 1/2-minute sequence is a terrific example of editing and camera trickery. The director of photography was Walter Lundin, who did many of Lloyd’s films,  including “Safety Last!” and the editor was T.J. Crizer, who also worked on “Safety Last!”

Let’s take this sequence apart and see how they did it without CGI. Keep asking one simple question: “Where is the camera in this shot?”

The setup: Lloyd’s character is trying to avoid being caught on a train, so he climbs out a window.

Lloyd climbs to the roof of the railroad car. Ask yourself: “Where is the camera?” Obviously, this is a set.

Back in the railroad car: Drat! Where did he go?

Reaction shot from Lloyd: Ha! I fooled them!

The porter closes the window.

Uh-oh! Trapped.

Lloyd on top of the train – which begins moving.

Notice these objects on top of the train. These will be important later.

Meanwhile, oblivious to what is happening on the roof of the railroad car….

OK, “where is the camera?” If this were reality, the camera would have to be on an adjacent moving platform.

This is actually a set with a mockup of the railroad car. The rapidly moving background is nothing but a “revolve,” a endless loop of painted scenery to give the impression of motion. To add to the appearance of a moving train, the mockup is being bounced up and down as if it’s in motion. Notice that the vent on the mockup doesn’t match the roof of the actual railroad car.

And for an extra dash of realism, let’s add a wind machine or two.

Cut away to someone on the roof of a train.

Back to the set!

A shot from the roof of the train, possibly taken from the top of the locomotive, showing what Lloyd would see.

Lloyd gets a cinder in his eye. Notice how tacky the “revolve” looks in screen captures. Obviously, nobody planned on someone dissecting this sequence 92 years later!

Back to a medium shot of Lloyd on the mockup of the train car.

He almost falls off the train – but it’s just a mockup.

Whew! He catches himself and gets the cinder out of his eye.

Ah! That’s better…. but wait!

Uh-oh! As realistic as this looks, we’re being fooled. We can tell because the vent he’s hanging on to doesn’t look that way on the actual train. If I were going to do this shot using 1920s technology, I would build a second mockup on a flatbed truck and have it drive close to the edge of a canyon. How ever they did it, we are being fooled here.

Gag shot. His heart is thumping in his chest.

Reaction shot on the mockup of the railroad car.

Looking down.

A long reaction shot.

A continuation of the shot from the top of the second mockup.

Lloyd climbs back up to the roof of the first mockup car.

Back to the set and the first mockup.

Lloyd almost falls off the car – but it’s only a fake.

Hanging off the second mockup car – another angle.

Back to the first mockup.

Lloyd as seen from the front of the train. Notice we suddenly have mountains! This is the only sequence when we can be certain he was photographed on a train. (Correction: It’s the second time we can be certain he was on a train. There’s a quick shot of him on the roof earlier in the sequence).

Reaction shot because he sees….

Uh-oh!! The camera is on the roof of the train.

Reaction shot … continued. Lloyd turns and starts to run for the back of the train.

New angle. The camera is at the side of the tunnel.

Someone is on the roof of the train. Notice that the real car doesn’t match the vent and valves that were on the roof of what was clearly a mockup.

A great stunt. But there’s no way to tell whether this is Lloyd or a double.

Another view from the roof of the train.

A closer angle. The film is speeded up at this point, but I’m not enough of an expert to know if the camera operator “under-cranked” or it was manipulated in some other way. Because of the distance and the speeded up film, it’s impossible to tell whether this is Lloyd or a double.

Back to the previous angle, still running.

Until he gets to the back of the train and dives for the roof.

The train comes out the other side of the tunnel…

… and Lloyd, covered with soot, is clinging to the back of the train mockup.

And he drops down to the back of the train.