The Senate Intelligence Committee met yesterday to take up its investigation of CIA Director William J. Casey for the first time in three months and decided there was still a bit more investigating to be done.

"There are a few little things hanging which we hope to clear up by the middle of next week," Chairman Barry Goldwater (R-Ariz.) told reporters after the closed-door session.

He added, however, that the committee does not expect to complete its report on the inquiry into Casey's financial activities, which it began in mid-July, until the end of November. Goldwater said the report would be "lengthy" and he reiterated a pledge to make it public.

Sen. Daniel Patrick Moynihan (D-N.Y.), the vice chairman, said the panel agreed on what remains to be done but declined to characterize the matters still under review.

The Washington Post reported earlier this week that the committee recently asked for internal Treasury Department documents concerning Casey's legal work for the government of Indonesia in 1976, in an effort to determine whether he should have registered as a foreign agent.

Casey and his New York law firm, Rogers & Wells, were enlisted by the Indonesians to seek foreign tax credits for payments from U.S. oil firms. Rogers & Wells subsequently registered as agents for Indonesia, in 1977, but Casey has taken the position that this was simply done out of an abundance of caution and that his own work on the case had already ended.

The CIA director did not submit a full five-year list of his clients, as Senate Intelligence Committee rules required in connection with his confirmation proceedings, until after the investigation was started.

The senators also accepted the resignation of staff director John F. Blake, who is leaving for another job, and named Robert R. Simmons in his place. Simmons, a CIA operations officer from 1969 to 1979, has been working on the committee staff for the past six months as the representative of Sen. John Chafee (R-R.I.).