-Two parters on the same disc. Many mid season 2 parters ended up split across 2 discs on the DVD sets. With the flexibility offered by increased storage space, PLEASE organize the episodes and special features so that 2 parters can be watched back to back without switching discs. (would including the S3 cliffhanger at the start of S4 be too much to ask? Probably.
The episodes are being presented in chronological order which, sorry, is probably going to split two-parters across discs. The only alternative is re-arranging the episodes out of order which would a)be illogical b)may cause continuity issues.