AFTER FLYING PSNL OF ENTERTAINMENT GROUP TO LINDBERGH FLD, ACFT WAS PSND TO NRBY BROWN FLD, SINCE LATE DEP WAS PLANNED AFTER NOISE CURFEW WAS IN EFFECT AT LINDBERGH. PLT TALKED WITH FSS SPECIALIST (SPLST) 3 TIMES BFR TKOF. HE RPRTD HE DID NOT HAVE INST DEP PROC FM ARPT. SPLST READ DEP PROC ON PHONE. ON LAST CALL TO FSS, PLT SAID HE PLANNED TO DEP VFR TWD NE & OBTAIN IFR CLNC AFTER AIRBORNE. (THIS RTE WAS TWD MTS.) DRG CALL, PLT EXPRESSED CONCERN ABT REMAINING CLR OF TCA & INQUIRED ABT STAYING BLO 3000'. SPLST AGREED WITH PLTS CONCERNS, BUT AFTER ACDNT, SPLST SAID HE THOUGHT PLT WAS REFERRING TO 3000' AGL, RATHER THAN 3000' MSL. PLT HAD FILED TO TKOF AT MIDNIGHT, BUT DIDN'T GET AIRBORNE UNTIL 0141 PST. SINCE FLT WAS OVR 1.5 HRS LATE, IFR FLT PLAN HAD 'CLOCKED OUT.' AS CTLR WAS REENTERING FLT PLAN IN COMPUTER, ACFT HIT RISING TRRN NR TOP OF MTN, ABT 8 MI NE OF ARPT AT ELEV OF ABT 3300'. NO DEFICIENCIES WERE FND WITH ACFT OR ITS ENGS. COPLT HAD NO TYPE RATING FOR THIS ACFT, THO HE RPRTDLY HAD MADE 3 TKOFS & LNDGS IN HAWKER-SIDDELEY DH.125.