I don't mean the film, but thanks to another message board I go to, someone posted this from Roseanne's blog (which you have to be a member of to see):

I always thought the guy was drinking heavily when I watched the show, especially in later years, but I thought his somewhat weird behavior on the series was not necessarily drugs, but just a very odd personality which had gotten him the part.
And shame on Speilberg for not trying. With Speilberg's money, he could have Goodman kidnapped and no one would ever know it. Have him taken to seclude island with a hired professional to clean Goodman up. And I wouldn't hold it against him one tiny bit, instead he helped bring us Indy 4. Yay Speilberg.
to John Goodman. Shame too -- he could have been so much more with his talent for humor and, having watcheds the series a LOT lately, some surpring acting abilities.
"laurie did not want to do the show if I was fired, which they tried to do. John went along with her, after he thought it might make him look bad not to. John hated tom arnold, and would huff and puff and leave the set whenever tom came down there. I just read in the ny times that they are best friends now. Both of them were huge addicts and I got caught in the middle of that. I used to look up goodman's nose in the scenes we did together and see white powder all over in there. I tried to call everyone who could help john try to get off dope and booze. He hated me for that. he use to throw parties at his house each weekend and invite everyone on the show but me. I was very hurt at the fact that I wrote his part and his lines for him and he never appreciated the work I did for him at all. He used to come in and scream at the little kids and drink til he fell over, and expect me to cover it all up for him, which I did. I was used to doing that, living with a drunk drug addict like tom arnold. I just tried to do the show and write the stories that I wanted to do on tv, despite the horrible stress and pain that both tom and john caused me every single day on the set. I was relieved when goodman left the show, and couldn't wait to kill his character off, so that I never had to be forced to work with him ever again. Beside tom, I have never met a more horrible person than john goodman. He is lucky that he is such a great actor or I would have fired or killed him. He never said anything nice or complimentary to any other actor. He put his drunk fist through a wall over michael fishman's head when michael was just six years old. I threatened him that I would go to the press more than once, and like all addicts, including his now best buddy tom, that scared him. they do not want the truth about themselves ever to be told. the truth is that john was an ******* like no other *******, and I just looked the other way as he bad mouthed me the show, the writing, and tom arnold daily. If I had to do it all over again, I would have picked someone else to play dan connor. someone who was more of a decent human being, and maybe less of a talented actor. John tried to apologize to me later, drunk at a benefit, telling me he made a mistake during the last few seasons of the show by hanging around with speilberg and big directors that he thought would be more beneficial to him than coming to work on the show. He asked me to consider writing another part for him and me. I said "get sober first", as he was sweating and falling over while he tried to flatter me. It is just perfect that he is now tom arnold's best friend, absolutely perfect in the scheme of soulless hollywood ******* users and vampires. I called speilberg when john was doing the flintstones and said "You need to help John before he drops dead like belushi did". Steven promised me that he would try, and john continued to deny that he did coke or that he drank during tapings all the way to the end. He would stand there sweating and staggering and we had to cut his lines to one or two sentences during season 8-9. I remember once he said he couldn't come to work because he was doing a shakespeare play in san diego instead. i went to see him, and could tell he was drunk as a mother****er in that too. I felt sorry for him, but pissed off at the way drunks and addicts wipe their asses with people who care about them. To this day, he has never apologized to me or anyone else who went out of their way to help him make millions. When i read that he and tom are the best of buddies now, I just thought "**** them both, for the misery and the contempt they showed me and everyone else on the roseanne show." I almost killed John for the way he treated Michael, who was just a baby. I have to say here that there were days when John would come to set and do these impromptu sketches that were unbelievably funny and left me and the cast gasping for air, and laying on the floor howling. He was as hilarious and brilliantly funny as he was difficult and mean.
every single hollywood expo about me is bull****. None of them ever discuss the drug addict husband who was busy selling stories about me for drug money to the tabloids, or the drug addict co star who put me through hell every day on the set, talking loudly about what a ***** my then husband was. Tom used to say john was using, and john used to say tom was a talentless golddigger, who was getting movie parts that should have gone to him. both of them hated each other, and when tom would be on the show john would leave the set and hold court in his dressing room with my crew who he liked to entertain and drink and drug with. both tom and john constantly ran to me to rat the other one out, and I had to handle that and do the show, plus try to keep everyone else happy at the same time. All I got for that was called a diva and a bitch. I hate hollywood *******s!
I never told anyone any of this, because I learned that Hollywood is a boy's club where no boys are ever held responsible for anything that they do, but all women who are creative are destroyed like a witchburning. (unless you are black, and then you are stolen from and destroyed even if male).
I am lucky i didn't die of heart failure or stress during the show. But, I didn't and I am still here happy to tell the truth of the bull**** and carnage that I lived through, and the *******s who enriched themselves at my expense. They wouldn't so much as piss on me if I was on fire. Do I care about any of it now? No, I honesly do not in the least. I survived them all. I have rid myself of *******s. I find that the most talented people in the world are gentle and ethical. I am glad i lived to find that out.
I am thankful that I was able to hang onto even a small percentage of the money that I 'made', and that I am sitting in the sacred kingdom of hawaii because of it with my partner johnny who makes me happy everyday, and my ethical decent children and grandchildren, none of who even consider going into show biz, as they value goodness and integrity instead."
Source

I always thought the guy was drinking heavily when I watched the show, especially in later years, but I thought his somewhat weird behavior on the series was not necessarily drugs, but just a very odd personality which had gotten him the part.
And shame on Speilberg for not trying. With Speilberg's money, he could have Goodman kidnapped and no one would ever know it. Have him taken to seclude island with a hired professional to clean Goodman up. And I wouldn't hold it against him one tiny bit, instead he helped bring us Indy 4. Yay Speilberg.
