Samsung's first Unpacked press event of 2021 introduced the Galaxy S21 series to the world, along with the wealth of new technology and functionality that they bring to the table.

However, for all the facts, figures and features shown off during the presentation - Samsung failed to touch on a few key aspects of its new flagships (and new accessories), which have since come to light by digging through product pages and asking the company directly.

The Galaxy S21 has a plastic back

Perhaps one of the biggest unmentioned aspects of the S21 line during Unpacked was that while the fronts of all three phones and the backs of the S21+ and S21 Ultra come dressed in Corning's latest Gorilla Glass Victus, the base S21 sports a reinforced polycarbonate back instead - that's plastic to you and me.

Samsung made the same move last year with the base Galaxy Note 20 and the Note 20 Ultra, but the decision to omit mention of this difference during the launch is what stands out. There's nothing inherently bad about opting for plastic over glass - it makes a device more lightweight, it's more impact resistant and allows for greater colour control - but Samsung is almost knowingly embarrassed or worried about being called out for the material difference.

The displays on the S21 and S21+ top out at Full HD+ resolution

Last year we bashed Samsung for locking users into choosing between enjoying content at the S20 range's native WQHD+ resolution or its maximum supported 120Hz refresh rate, this year, Samsung has taken that choice out of users' hands entirely.

The Dynamic AMOLED 2X panels on both the S21 and S21+ top out at Full HD+ resolution natively, meaning they're not quite as sharp as the panels on last year's phones but you can at least enjoy 120Hz without question.

Thankfully, the S21 Ultra retains a WQHD+ resolution and now supports an adaptive refresh rate simultaneously; meaning you can enjoy sharper high definition content at up to 120Hz, without question.

The Galaxy S21 line lacks expandable memory

Expandable memory on a Samsung Galaxy flagship looks to have died with last year's Note 20 Ultra. All three of this year's Galaxy S21 family lack any expandable storage option, with Samsung instead leaning on its OneDrive cloud storage partnership with Microsoft.

The S21 and S21+ can be had with either 128GB or 256GB of internal space, while the S21 Ultra can also be had in a 512GB SKU.

The Galaxy S21 line tops out at 25W fast charging

Just as expandable storage died out with the Note 20 Ultra, so did charging faster than 25W with the S20 Ultra, it seems.

All three of this year's Galaxy S phones support up to 25W wired charging and the USB PD 3.0 standard, along with wireless charging up to 15W and reverse wireless charging - dubbed Wireless PowerShare at 4.5W.

It's also worth reminding that this year's Galaxy S phones don't include a power adapter (or headphones) in-box and that Wireless PowerShare won't work if you device has below 30% charge itself.

The mmWave models are heavier

In regions where mmWave 5G is available to consumers and Samsung is selling mmWave-capable SKUs of the S21 line, all three models weigh two grams heavier a piece - presumably as the result of an additional antenna system.

8K Video Snap produces a 33Mp photo

The camera setup across this year's Galaxy S21 series continues support for 8K video capture at 24 frames per second. The 8K Video Snap feature lets users pull stills from 8K footage with the tap of an icon.

While these stills were described as "high quality" on stage, the actual resolution of an 8K Video Snap clocks in at 33Mp.

Galaxy SmartTags only work with Samsung Galaxy devices

It wasn't made explicity clear on stage but it turns out Samsung's new Galaxy SmartTag (and forthcoming SmartTag+) location trackers need to be tied to a Samsung account to function and can only be located using a Samsung Galaxy device.

There was question about whether or not any Android device would be able to support the accessory but it seems that isn't the case, making them a little less versatile compared to notable rival Tile's trackers.

Galaxy Buds Pro's Auto Switching feature is exclusive to Galaxy devices

One of the impressive new technologies that comes as part of the experience in Samsung's new Galaxy Buds Pro true wireless buds is their ability to automatically switch audio source, based on user needs.

If you're watching a movie on your tablet and a call comes through on your phone, the Buds Pro will instantly shift their connection from one device to the other so you can take your call hands-free, and simply re-establish the connection with your tablet when your call is over - without you having to do a thing.

It might not come as a huge surprise, but this isn't just a Galaxy-exclusive feature (we'd hoped it might work across different Android devices, at least), it requires that all the devices in question are running the company's latest OneUI 3.1 and that they're also all logged in to the same Samsung account.

Read next: Where to buy the Samsung Galaxy S21, S21+ and S21 Ultra