(SPOILER WARNING)
Too make this review short, there's nothing really happened to this Episode 11.5 and it is not carried over what happened after the Film Project. But, there are some important details on this OVA... besides the obvious fan service of the characters depicted in this one.
First of, Houtarou has gotten into a side-job as a lifeguard in a local pool, for 5000 yen (US$5), thanks to his older sister's offer. Which is the first time we'll see Houtarou busts his ass for a while after shutting himself inside his house doing almost nothing. So he had to do it. Besides, it's just a one-time job and he can actually get paid by sitting only at the umpire chair. So, as Houtarou finally accepted this offer, the rest of the club wanted to see the surprise turn of events as Houtarou finally works in the sidelines.
Second, Houtarou's older sister, Tomoe, finally got home after her trip from India. And recommends her younger brother to do sidelines for a while. We also see how close the two siblings were in this episode like the other main episodes that was shown on the series.
Third, there are some hinted relationship development for Mayaka and Ibara. Yes, they were already been revealed and developed on the other episodes as well. And, chronologically, here on this OVA, a little tease of what to come for them as Houtarou wants Mayaka to be carried by Ibara for the sake of the investigation.
Speaking of the investigation, in this OVA, they just investigate the "lost" earrings of a woman that could be around the public pool. If they haven't found it, there might be an accident waiting for them to happen. Which is a predictable investigation to me as it was already hinted earlier in this episode that the kid once "Ice Cream" and Chitanda noticed that the woman's white "earrings" got missing overtime. Hinted that she carried her child with an ice cream on his hands and did not intend to put a hit of an ice cream to his mother's right earlobe.
Overall, yes, as expected on other OVAs, Chitanda's silky-white... err... swimsuit is DEFINITELY you shouldn't want to miss!!! Forget Mayaka... If I wish I would have a chance to get crushed by Chitanda's white thighs, I'm surely going to be in the heavens. But besides that, the story is... ehh, it's alright. There's little to no character development here and it's just a simple fan-service episode.
Is it worth while to watch? Not Really, there's nothing really much happening on this episode... But still watchable though.