This film takes a WILD Genre Shift from fairly standard Western to fairly standard monster flick. While there are mentions of "the beast" from the first scene of the film, a lot of the references to said beast feel shoehorned in. As stated elsewhere, one could remove the T. rex from the film entirely and lose nothing except for the deaths of two characters. What if the film's script did start out as a completely standard Western, but then some studio executive said something along the lines of, "I want to make a monster movie, let's take this preexisting script and throw a monster into it"? Similar things have happened with films of that era. For example, when Ed Wood was making Bride of the Monster, one of the backers said he would fund the film only if a nuclear bomb went off at the end — thus leading to that film's bizarre out-of-place ending.
WMG / The Beast of Hollow Mountain
This whole movie happened from Executive Meddling.