Some train icons (teardrops) have black outlines (silver, orange, yellow). Others have white outlines (blue, red, green). They should be consistent. Probably no outline would be best.
Right now I fetch all trains, alerts and predictions no matter what filters you have set. This is great when on a desktop or wifi since you get really snappy results when toggling filters on and off. But it's not so great for mobile users who have limited data. Add a toggle to only fetch data that is immediately needed.
https://www.dcmetrohero.com/apis
The MetroAlerts API provided by dcmetrohero has station codes associated with each alert (unlike WMATA's API). Evaluate the accuracy of this API and come up with a way of displaying affected stations.
The height restrictions cause unnecessary scrolling on desktops when there are many alerts or when you've clicked on gallery place / metro center without any filters. The height restrictions currently exists to prevent screwy layout stuff on mobile but using a media query that can be fixed for desktop.