Do you have a screenshot of when the tanks are first introduced in the film? Because it could also be they just mirrored the picture for whatever reason. You should be able to tell quickly enough from seeing which side of the turret the commander's cupola is on.

Probably.

Well, if you were to go for "accurate" (as far as possible with these toon models, of course), then you've got the wrong type of Sherman anyway  Your model is a small-hatch M4A1 (75 mm) while Oddball's tank is a large-hatch M4A3 (75 mm) rearmed with a 76 mm gun.

In the film, he comments that he had a pipe put over the gun to make it look like a 90 mm. You could do that on your model easily, too.