Accidentally Accurate: Ichika in the novels always called the cuteSleepyhead girl with the long sleeves "Nohohon-san", which roughly means "Ms. Whatever" since he didn't know her name. On her end, she thinks he's calling her a shortened version of her real name. When Ichika finally admits he doesn't actually know her name in Volume 5, she gets upset, though she gets over it fast. Her real name is Nohotoke Honne, which meant Ichika was getting it pretty close the whole time.
Acting for Two: In the English dub, Chifuyu & Madoka are both played by Luci Christian. It's almost certainly due to the fact that Madoka looks like a slightly younger Chifuyu.
As to Laura, her eyepatch is on the left eye instead of the right and she initially didn't use knives, perhaps to avoid making her look and sound any more like Cinque than she already does. In the second season, her knives start seeing a lot more use.
Meanwhile the dub, it's apparently changed to resemble another eyepatch-wearing Tyke Bomb.
The Other Darrin: Not for the voice actors, but for the illustrators. Okiura has been I.S's illustrator for the first seven volumes. From volume 8 onwards (as well as reprints), CHOCO replaces Okiura as illustrator as part of the author switching publishing companies.
Double for the animators: Media Factory was tasked with animating the story, until Overlap took over by the second OVA and season 2.
And also in Nisekoi as Raku Ichijou and Kosaki Onodera, respectively.
No Export for You: Averted with the anime series (both Season 1 and Season 2). Meanwhile, as for the novels, while there was a group that fan translated them up to Volume 8, the translating group itself was becoming quite irritated at the story's pacing and incessant fanservice, and as of now there are no active translators for Volume 9.
Schedule Slip: Due to the author's health, the sixth novel was delayed until December 2010, which was a six month gap between Volumes 5 and 6. Before this, the volumes had never been more than three or four months apart.
After Volume 7 was published in April 2011, the author apparently had some kind of dispute with his publishing company. The result was that Volume 8 didn't get published until April 2013. In June 2013, Yumizuru mentioned (in an author's note in the reboot manga's 1st chapter) that he was working on Volume 9, but it still has yet to be released.
Volume 9 was finally released on April 25, 2014, exactly one year after Volume 8.