ID4 came out in 1996, and even then it stretched credulity, not to believe in extra terrestrials, who had mastered intergalactic flight, but that Jeff Goldblum, without knowing anything about the aliens' computer language, could write a "virus" that would infect their computers.
Here it is, 19 years later, and IMHO, it gets worse!
Goldblum & Smith fly the infamous UFO that crashed in Roswell back in 1947 up the the mothership to upload the virus. Again, I remind you that these aliens are intelligent enough to travel between the stars, and not only are they dumb enough not to install a simple anti-virus software on their computers, they're so stupid that if a fifty year old ship flies up to meet them, they are apparently oblivious to that fact, too.
Just for comparison, suppose you're the captain of the USS Ronald Reagan, and a 50 yr. old plane with US Navy markings attempts to land upon the deck. Let's say a Grumman F8F Bearcat. Modern aircraft "squawk" an 'Identification Friend or Foe' (IFF) code. Even if this 50 year old plane was equipped with IFF, (which it wasn't), would it be the right code? After fifty years?? As Captain, what would you do? Yeah. Me, too!
Can't we imagine that any being smart enough to cross interstellar space could have figured out a way to identify their craft, and maybe even keep track of them? Or know the ship that just landed hadn't taken off from their vessel or any sistership in 50 yrs?. Or maybe even notice the lack of any possible change or improvements over a fifty year span? Stupid aliens!
The movie's characters are likeable. The disappointments however,are richly layered for those who care to look.