**Please note that there are spoilers for Captain America: Civil War and Captain America: Winter Soldier in this short article**
The MCU is a big place and it is very easy to miss or remember small details. Here is one small detail that if seen before hand, Zemo's quest for information on a date would have been very obvious.
If you have seen Captain America: Winter Soldier, then you might remember the seen with the computerized Arnim Zola.
Here, when Zola was talking to Cap and Black Widow, it was revealed that HYDRA infiltrated S.H.I.E.L.D. During this time Zola shares that HYDRA secretly killed anyone who opposed them.
This flashes very quickly.
After this, Zola says "accidents happen" and these images flash.
With the first image (Winter Soldier's Arm) shown and the last image (Nick Fury "Deceased") shown, we can see that there is a connection. Plus, earlier in the movie everyone saw that Fury's "death" was not an accident. The Winter Soldier shot Fury. With Howard and Maria Stark's accident being shown in between these two points, it is implied that The Winter Soldier killed them. If you look at the date on the news paper, it might look familiar if you subtract one day.
Please let me know your thoughts in the comment section down below and have a Marvelous day.