That Crystal Skull scene with jungle-chase-fight indeed felt very "artificial" now that I remember back. I also remember this weird greenish hue throughout the chase scene, which didn't help things.

It's surprising that in the original trilogy, the chase scenes were limited significantly by technology yet they produced better believability than the CGI-rich Crystal jungle action. But people had issues with the fictional Soviet jungle-killing machine with the cutters? I mean, that problem was small compared with the whole jungle chase framework.