Kanada drew the fleeing backgrounds characters. Not sure who's in charge of the rest. I'm also at least 50% sure that Studio Z worked on more than one episode since MAL and ANN credit Kanada for other episodes and I swear I can remember drawings like his elsewhere in the show but I can't be arsed to find anything else because it's not listed on his sakugawiki page.

According to seesaawiki スタジオ・Z worked on #01 and #04 only

pilo said:
Kanada drew the fleeing backgrounds characters. Not sure who's in charge of the rest. I'm also at least 50% sure that Studio Z worked on more than one episode since MAL and ANN credit Kanada for other episodes and I swear I can remember drawings like his elsewhere in the show but I can't be arsed to find anything else because it's not listed on his sakugawiki page.

Studio Z also worked on episode 4, however this is probably Kanada's only work on the series as he said in a special that he was busy with movies at the time which is also why he only did the background characters.

「ちょうどそのころ劇場の仕事が入ってきたんで、そっちのほうをやってたと思うんですよ。『銀河鉄道999』とか」とコメントしている。

He didn't work in the show besides the first episode. Also, studio Z worked on more than #01&#04 but the studio name is not in the credit

pilo said:
Kanada drew the fleeing backgrounds characters. Not sure who's in charge of the rest. I'm also at least 50% sure that Studio Z worked on more than one episode since MAL and ANN credit Kanada for other episodes and I swear I can remember drawings like his elsewhere in the show but I can't be arsed to find anything else because it's not listed on his sakugawiki page.

Half true. Osamu Nabeshima and Shigenobu Nagasaki (both given Studio Z affiliation for episodes 1 & 4) are present for later episodes, credited together I may add, despite the studio itself not being listed. I think the Kaneda credit's an error though since I can't find any other information about working past this episode beyond those two sites.

If I had to guess who else worked on this scene, it might be Nabeshima. But again, it's just a guess.