Other mistake: The janitor, Howard, stops Dr. Stone to talk to him about the loss of his son. Look at his badge; the person on it sports a beard and sideburns and a hat, and it's "Jensen" plus initial. Later on the same janitor hears a noise inside the lab and you can see the badge picture is different and it lists the full first and last name. The first scene was a Whedon reshoot, so probably after weeks they didn't have the original prop and made another one. (00:18:55 - 00:21:15)
Other mistake: The security guard alerts Batman about Barry Allen's arrival pushing a button on his phone. The date on the phone says it's Friday 20th Jan, which is coherent with the year (2017) this version of the movie is set in, but too early for the K-pop "As if it's your last" music video playing in Flash's lair (it was a summer release). (00:16:50)
Answer: I don't know about the Ben Affleck portion of your question, but when the film was going back for reshoots, Henry Cavill had grown a mustache for his upcoming role in "Mission: Impossible Fallout" which he was contractually obligated to keep. The special effects crew had no choice but to digitally erase his mustache in post-production, which is why his mouth area looks so odd in some scenes (if you have seen the trailer for "Deadpool 2," Deadpool makes reference to this when he notes that the special effects for Cable's metal arm are not finished, and remarks that it's not like they are trying to remove a mustache). Interestingly, a person on YouTube posted a video of them removing Henry Cavill's mustache using a $500 computer, and it looks remarkably better than what this film did with a $300 million budget.
Phaneron ★