Ghost Town - How Did They Miss That?

I just watched 'Ghost Town' starring Ricky Gervais and Téa Leoni. It isn't actually a bad film as such, it has funny bits and the re-working of the Scrooge story is not too close to the original, so that's okay. However they irritatingly miss a great plot opportunity in the middle of the movie. Téa Leoni's character is working on a mummified Egyptian and being assisted by a guy who can see ghosts. Obviously we expect to see the ghost of an ancient Egyptian following his mummy around. The writers somehow completely missed this great plot opportunity and the ancient ghost never appears. The mummy is quickly forgotten as the story moves on. A pity. It could have been a funnier movie. Instead it was just so-so.