I'm probably going to make myself quite unpopular, but I don't think it's very good. I think the idea is brilliant, but the execution leaves something to be desired.
The joke in the first comic isn't immediately obvious, further evidenced by the fact that you felt the need to explain it, and the colour filter makes the whole thing look washed out.
The second one is better, despite being clearly influenced by the jokes in Concerned, but the image isn't particularly funny on its own and the postcard, while a nice touch, isn't snappy enough. Much of your humour is going to derive from them not realising that they are in an oppressive junta. I think something like this would have been better:
"Dear Red Team,
Thanks for letting has some time off, I hope Scout is feeling better. Heavy and I have just arrived in City 17. We had a little trouble in customs, but that's all fixed now. It is very peaceful here, everyone going about their business in such an orderly fashion! The local police are having a crackdown on litter and we were happy to help out. The locals are very friendly, but have advised us not to drink the water. I'm glad we brought sandvitches!
Anyway, must go now. It has been a long day and Heavy is starting to get tired.
See you soon
Medic"
I really hope you continue with these, but rather than try and do loads at once, slow down and make sure you've worked out the joke before you start doing anything. I'm not trying to be a dick, just give some constructive criticism. Look forward to seeing where you go with this.