At 1:08, holes previously carved in the ice wall are clearly visible above Mr. Ice Man as he clumsily works his way up. He conveniently places his war club into these cavities because there is no way he would be able, with this tool, to even scratch the super hard ice that sits compacted deep inside a glacier.
In the film the Berkshire pig is discernible. This is a British breed (a rare breed) of pig originating in the early 19th century, thus, it could not have been there in the Alps more than 5000 years ago.
Jet contrails are visible in the sky. (1:01:28) Jets weren't making contrails back then.
The butt of a sawn tree limb is visible in one scene (13:03)