Despite abysmal reviews from critics, Batman v Superman: Dawn of Justice still managed to rake in $166 million domestically in its opening weekend, the biggest ever for a March film release and the fifth-biggest movie opening ever.

That being said, there is reason to believe Batman v Superman's momentum may be slowing considerably as it moves into its second weekend. According to Forbes, the film saw a 55 percent attendance drop from Friday to Sunday its opening weekend. About 38 percent of that drop came between Friday and Saturday, with the remaining 27 percent coming from Saturday to Sunday.

It's the biggest attendance drop in modern superhero movie history, even more so than critical flops like the recent Fantastic Four reboot. The only other film with a comparable attendance drop is The Dark Knight Rises, which saw a 47 percent attendance drop (and one that could have been affected by the 2012 Aurora movie theater shooting).

So what does that mean for Warner Bros. and DC Comics? Less money. Though the film will no doubt do moderately well, Forbes says if the attendance trend continues, the movie that serves as the tentpole for the entire DC cinematic universe could come in at a total worldwide gross of around $400 million. DC Comics fans may have flocked to the theater opening day to see Batman, Superman and Wonder Woman share the silver screen, but poor word of mouth and awful reviews may keep more casual fans from paying money for a ticket.

Of course, $400 million wouldn't be a small amount of money any way you look at it. However, with a production budget of $250 million, plus the cost of all the marketing associated with the film, the actual payday for Warner Bros. might not be as big as you would think.

There is also Marvel to consider. Compared with the $623 million earned by Marvel's first Avengers movie, $400 million for the movie that will kick off the cinematic Justice League isn't exactly a great start. If Batman v Superman's box office trend continues, it might make it clear who the winner is between the two comic book giants.