It's only arbitrage when there is no possibility of the price going lower than it is at the moment (e.g. a stock priced at 100 has already reported box office of 110). Warrants and stocks for a movie trade independently of each other and are both based on trader's view of what will happen over the next few weeks - it is possible that the stock in question absolutely bombs and only makes $20 million, in which neither the movie stock or the warrant will give any profits (unlikely, but possible).
You'll often see the OW, Call and/or Put derivatives move in a different direction to the movie stock over a day and seem to contradict each other. As they all are priced independently, it all depends on where traders see the profit being based on the current price for each commodity.